refactor(lib): move generic hooks, DnD engine, shortcut contract to lib

Continue M4 lib/ de-flattening with domain-agnostic infra:
- lib/hooks/: 9 pure generic hooks (useDebouncedValue, useIsMobile,
  useLongPressAction, useRangeSelection, useResizeClientHeight,
  useWindowVisibility, useSystemPrefersDark, useVirtualizerScrollMargin,
  useRemeasureGridVirtualizer) — all PURE (only react/zustand/tanstack deps).
- lib/dnd/DragDropContext.tsx: the generic mouse-event DnD engine (WebKitGTK
  HTML5-DnD workaround, ~24 importers, self-contained) — empties src/contexts/.
- lib/shortcuts/: shortcutActions + shortcutTypes (the action-id + binding
  contract; registry/dispatch/bindings stay app-level and import the contract,
  app->lib direction).

useWindowFullscreenState deliberately NOT moved — kept in hooks/ as app-shell
per the handoff iron-rule list (overrides its pure-helper appearance).

Pure move via deep @/lib/* specifiers. tsc 0, lint 0/0, full suite 319 files /
2353 tests green.

src/features/album/components/AlbumCard.tsx

@@ -17,9 +17,9 @@ import { resolveCoverDisplayTier } from '@/cover/tiers';
 import { acquireUrl } from '@/utils/imageCache/urlPool';
 import { OpenArtistRefInline } from '@/features/artist';
 import { fetchAlbumTracks, playAlbum, playAlbumShuffled } from '@/utils/playback/playAlbum';
-import { useLongPressAction } from '@/hooks/useLongPressAction';
+import { useLongPressAction } from '@/lib/hooks/useLongPressAction';
 import { LongPressWaveOverlay } from '@/components/LongPressWaveOverlay';
-import { useDragDrop } from '@/contexts/DragDropContext';
+import { useDragDrop } from '@/lib/dnd/DragDropContext';
 import { isAlbumRecentlyAdded } from '@/features/album/utils/albumRecency';
 import { albumArtistDisplayName, deriveAlbumArtistRefs } from '@/features/album/utils/deriveAlbumHeaderArtistRefs';
 import { coverServerScopeForServerId } from '@/cover/serverScope';

src/features/album/components/AlbumHeader.test.tsx

@@ -16,7 +16,7 @@ vi.mock('react-router-dom', async importActual => {
 vi.mock('@/cover/useLibraryCoverRef', () => ({ useAlbumCoverRef: () => undefined }));
 vi.mock('@/cover/lightbox', () => ({ useCoverLightboxSrc: () => ({ open: vi.fn(), lightbox: null }) }));
 vi.mock('@/features/album/hooks/useAlbumDetailBack', () => ({ useAlbumDetailBack: () => vi.fn() }));
-vi.mock('@/hooks/useIsMobile', () => ({ useIsMobile: () => false }));
+vi.mock('@/lib/hooks/useIsMobile', () => ({ useIsMobile: () => false }));
 vi.mock('@/store/themeStore', () => ({ useThemeStore: () => false }));
 vi.mock('@/components/StarRating', () => ({ default: () => null }));
 vi.mock('@/features/artist', () => ({ OpenArtistRefInline: () => null }));

src/features/album/components/AlbumHeader.tsx

@@ -7,7 +7,7 @@ import { CoverArtImage } from '@/cover/CoverArtImage';
 import { useAlbumCoverRef } from '@/cover/useLibraryCoverRef';
 import { useCoverLightboxSrc } from '@/cover/lightbox';
 import { useTranslation } from 'react-i18next';
-import { useIsMobile } from '@/hooks/useIsMobile';
+import { useIsMobile } from '@/lib/hooks/useIsMobile';
 import { useAlbumDetailBack } from '@/features/album/hooks/useAlbumDetailBack';
 import { useThemeStore } from '@/store/themeStore';
 import StarRating from '@/components/StarRating';

src/features/album/components/AlbumTrackList.tsx

@@ -4,7 +4,7 @@ import React, { useMemo, useState, useEffect } from 'react';
 import { useTracklistColumns } from '@/utils/useTracklistColumns';
 import { usePlayerStore } from '@/store/playerStore';
 import { useTranslation } from 'react-i18next';
-import { useIsMobile } from '@/hooks/useIsMobile';
+import { useIsMobile } from '@/lib/hooks/useIsMobile';
 import { useSelectionStore } from '@/store/selectionStore';
 import {
   COLUMNS,

src/features/album/hooks/useAlbumBrowseData.ts

@@ -38,7 +38,7 @@ import {
 } from '@/utils/library/albumBrowseCatalogChunk';
 import { useOfflineBrowseContext } from '@/features/offline';
 import { useClientSliceInfiniteScroll } from '@/hooks/useClientSliceInfiniteScroll';
-import { useDebouncedValue } from '@/hooks/useDebouncedValue';
+import { useDebouncedValue } from '@/lib/hooks/useDebouncedValue';
 import { useInpageScrollSentinel } from '@/hooks/useInpageScrollSentinel';
 
 const PAGE_SIZE = 30;

src/features/album/hooks/useAlbumTrackListSelection.ts

@@ -1,7 +1,7 @@
 import React, { useCallback, useEffect, useRef } from 'react';
 import type { SubsonicSong } from '@/lib/api/subsonicTypes';
 import { useSelectionStore } from '@/store/selectionStore';
-import { useDragDrop } from '@/contexts/DragDropContext';
+import { useDragDrop } from '@/lib/dnd/DragDropContext';
 import { songToTrack } from '@/utils/playback/songToTrack';
 
 interface UseAlbumTrackListSelectionArgs {

src/features/album/pages/Albums.tsx

@@ -26,7 +26,7 @@ import { Download, HardDriveDownload, Disc3, ListPlus } from 'lucide-react';
 import SelectionToggleButton from '@/components/SelectionToggleButton';
 import FilterQuickClear from '@/components/FilterQuickClear';
 import { usePerfProbeFlags } from '@/utils/perf/perfFlags';
-import { useRangeSelection } from '@/hooks/useRangeSelection';
+import { useRangeSelection } from '@/lib/hooks/useRangeSelection';
 import { useMainstageInpageHeaderTight } from '@/hooks/useMainstageInpageHeaderTight';
 import { useInpageScrollViewport } from '@/hooks/useInpageScrollViewport';
 import InpageScrollSentinel from '@/components/InpageScrollSentinel';

src/features/album/pages/LosslessAlbums.tsx

@@ -12,7 +12,7 @@ import { useOfflineStore } from '@/features/offline';
 import { useDownloadModalStore } from '@/features/offline';
 import { usePlayerStore } from '@/store/playerStore';
 import { useZipDownloadStore } from '@/features/offline';
-import { useRangeSelection } from '@/hooks/useRangeSelection';
+import { useRangeSelection } from '@/lib/hooks/useRangeSelection';
 import { useMainstageInpageHeaderTight } from '@/hooks/useMainstageInpageHeaderTight';
 import { usePerfProbeFlags } from '@/utils/perf/perfFlags';
 import { showToast } from '@/utils/ui/toast';

src/features/album/pages/RandomAlbums.tsx

@@ -22,7 +22,7 @@ import { invoke } from '@tauri-apps/api/core';
 import { join } from '@tauri-apps/api/path';
 import { showToast } from '@/utils/ui/toast';
 import { useZipDownloadStore } from '@/features/offline';
-import { useRangeSelection } from '@/hooks/useRangeSelection';
+import { useRangeSelection } from '@/lib/hooks/useRangeSelection';
 import { usePerfProbeFlags } from '@/utils/perf/perfFlags';
 import { albumGridWarmCovers, COVER_DENSE_GRID_MIN_CELL_CSS_PX } from '@/cover/layoutSizes';
 import {

src/features/artist/components/ArtistDetailHero.tsx

@@ -10,7 +10,7 @@ import { useOfflineStore } from '@/features/offline';
 import { useAuthStore } from '@/store/authStore';
 import { useThemeStore } from '@/store/themeStore';
 import { useArtistOfflineState } from '@/features/artist/hooks/useArtistOfflineState';
-import { useIsMobile } from '@/hooks/useIsMobile';
+import { useIsMobile } from '@/lib/hooks/useIsMobile';
 import { ArtistHeroCover } from '@/cover/artistHero';
 import { useArtistBanner, useArtistFanart } from '@/cover/useArtistFanart';
 import { backdropFromConfig } from '@/cover/artistBackdrop';

src/features/artist/components/ArtistDetailSimilarArtists.tsx

@@ -3,7 +3,7 @@ import { useTranslation } from 'react-i18next';
 import { useNavigate } from 'react-router-dom';
 import { ChevronDown, ChevronUp } from 'lucide-react';
 import type { SubsonicArtist } from '@/lib/api/subsonicTypes';
-import { useIsMobile } from '@/hooks/useIsMobile';
+import { useIsMobile } from '@/lib/hooks/useIsMobile';
 
 interface Props {
   marginTop: string;

src/features/artist/pages/Artists.tsx

@@ -9,8 +9,8 @@ import { useAuthStore } from '@/store/authStore';
 import { useTranslation } from 'react-i18next';
 import { useVirtualizer } from '@tanstack/react-virtual';
 import { APP_MAIN_SCROLL_VIEWPORT_ID, ARTISTS_INPAGE_SCROLL_VIEWPORT_ID } from '@/constants/appScroll';
-import { useElementClientHeightById, useElementClientHeightForElement } from '@/hooks/useResizeClientHeight';
-import { useVirtualizerScrollMargin } from '@/hooks/useVirtualizerScrollMargin';
+import { useElementClientHeightById, useElementClientHeightForElement } from '@/lib/hooks/useResizeClientHeight';
+import { useVirtualizerScrollMargin } from '@/lib/hooks/useVirtualizerScrollMargin';
 import { usePerfProbeFlags } from '@/utils/perf/perfFlags';
 import {
   ALL_SENTINEL,

src/features/favorites/components/FavoritesSongsTracklist.tsx

@@ -10,12 +10,12 @@ import { usePlayerStore } from '@/store/playerStore';
 import { previewInputFromSong, usePreviewStore } from '@/store/previewStore';
 import { useSelectionStore } from '@/store/selectionStore';
 import { useThemeStore } from '@/store/themeStore';
-import { useDragDrop } from '@/contexts/DragDropContext';
+import { useDragDrop } from '@/lib/dnd/DragDropContext';
 import { useOrbitSongRowBehavior } from '@/features/orbit';
 import { songToTrack } from '@/utils/playback/songToTrack';
 import { appendServerQuery } from '@/utils/navigation/detailServerScope';
 import { APP_MAIN_SCROLL_VIEWPORT_ID } from '@/constants/appScroll';
-import { useElementClientHeightById } from '@/hooks/useResizeClientHeight';
+import { useElementClientHeightById } from '@/lib/hooks/useResizeClientHeight';
 import { SORTABLE_COLUMNS } from '@/features/favorites/hooks/useFavoritesSongFiltering';
 
 interface Props {

src/features/miniPlayer/components/MiniPlayer.tsx

@@ -5,7 +5,7 @@ import { emit } from '@tauri-apps/api/event';
 import { invoke } from '@tauri-apps/api/core';
 import { useTranslation } from 'react-i18next';
 import { usePlayerStore } from '@/store/playerStore';
-import { registerQueueDragHitTest } from '@/contexts/DragDropContext';
+import { registerQueueDragHitTest } from '@/lib/dnd/DragDropContext';
 import MiniContextMenu from '@/features/miniPlayer/components/MiniContextMenu';
 import type { MiniSyncPayload, MiniControlAction, MiniTrackInfo } from '@/features/miniPlayer/utils/miniPlayerBridge';
 import {

src/features/miniPlayer/hooks/useMiniQueueDrag.ts

@@ -1,6 +1,6 @@
 import React, { useEffect, useRef, useState } from 'react';
 import { emit } from '@tauri-apps/api/event';
-import { useDragDrop } from '@/contexts/DragDropContext';
+import { useDragDrop } from '@/lib/dnd/DragDropContext';
 import { usePlayerStore } from '@/store/playerStore';
 
 interface Args {

src/features/miniPlayer/hooks/useMiniSync.ts

@@ -1,6 +1,6 @@
 import { useEffect, useRef } from 'react';
 import { emit, listen } from '@tauri-apps/api/event';
-import { useWindowVisibility } from '@/hooks/useWindowVisibility';
+import { useWindowVisibility } from '@/lib/hooks/useWindowVisibility';
 import type { MiniSyncPayload } from '@/features/miniPlayer/utils/miniPlayerBridge';
 
 interface ProgressPayload {

src/features/nowPlaying/components/NpCardWrap.tsx

@@ -1,5 +1,5 @@
 import React from 'react';
-import { useDragSource } from '@/contexts/DragDropContext';
+import { useDragSource } from '@/lib/dnd/DragDropContext';
 import type { NpCardId } from '@/features/nowPlaying/store/nowPlayingLayoutStore';
 
 interface NpCardWrapProps {

src/features/nowPlaying/pages/NowPlaying.tsx

@@ -13,7 +13,7 @@ import { useAuthStore } from '@/store/authStore';
 import { useLyricsStore } from '@/store/lyricsStore';
 import { songToTrack } from '@/utils/playback/songToTrack';
 import { useRadioMetadata } from '@/features/radio';
-import { useDragDrop } from '@/contexts/DragDropContext';
+import { useDragDrop } from '@/lib/dnd/DragDropContext';
 import OverlayScrollArea from '@/ui/OverlayScrollArea';
 import {
   useNpLayoutStore, NP_CARD_IDS,

src/features/playlist/components/PlaylistCard.tsx

@@ -8,7 +8,7 @@ import {
   displayPlaylistName, isSmartPlaylistName, type PendingSmartPlaylist,
 } from '@/features/playlist/utils/playlistsSmart';
 import { formatHumanHoursMinutes } from '@/lib/format/formatHumanDuration';
-import { useDragSource } from '@/contexts/DragDropContext';
+import { useDragSource } from '@/lib/dnd/DragDropContext';
 import { PlaylistCardMainCover, PlaylistSmartCoverCell } from '@/features/playlist/components/PlaylistCoverImages';
 
 interface Props {

src/features/playlist/components/PlaylistFolderSection.tsx

@@ -4,7 +4,7 @@ import { ChevronRight, Folder, Pencil, Trash2 } from 'lucide-react';
 import type { SubsonicPlaylist } from '@/lib/api/subsonicTypes';
 import { usePlaylistFolderStore } from '@/features/playlist/store/playlistFolderStore';
 import type { PlaylistFolder } from '@/features/playlist/utils/playlistFolders';
-import { useDragDrop } from '@/contexts/DragDropContext';
+import { useDragDrop } from '@/lib/dnd/DragDropContext';
 import { VirtualCardGrid } from '@/components/VirtualCardGrid';
 
 interface Props {

src/features/playlist/components/PlaylistTracklist.tsx

@@ -4,7 +4,7 @@ import PlaylistRow, { type PlaylistRowCallbacks } from '@/features/playlist/comp
 import { TracklistColumnPicker } from '@/components/albumTrackList/TracklistColumnPicker';
 import { useTranslation } from 'react-i18next';
 import { APP_MAIN_SCROLL_VIEWPORT_ID } from '@/constants/appScroll';
-import { useElementClientHeightById } from '@/hooks/useResizeClientHeight';
+import { useElementClientHeightById } from '@/lib/hooks/useResizeClientHeight';
 import { useNavigate } from 'react-router-dom';
 import {
   ListPlus, Search, Trash2, X,
@@ -15,7 +15,7 @@ import type { Track } from '@/store/playerStoreTypes';
 import { usePlayerStore } from '@/store/playerStore';
 import { previewInputFromSong, usePreviewStore } from '@/store/previewStore';
 import { useThemeStore } from '@/store/themeStore';
-import { useDragDrop } from '@/contexts/DragDropContext';
+import { useDragDrop } from '@/lib/dnd/DragDropContext';
 import { useOrbitSongRowBehavior } from '@/features/orbit';
 import { songToTrack } from '@/utils/playback/songToTrack';
 import type { PlaylistSortKey, PlaylistSortDir } from '@/features/playlist/utils/playlistDisplayedSongs';

src/features/playlist/components/PlaylistsFolderView.tsx

@@ -2,7 +2,7 @@ import React from 'react';
 import type { SubsonicPlaylist } from '@/lib/api/subsonicTypes';
 import { EMPTY_SERVER_FOLDERS, usePlaylistFolderStore } from '@/features/playlist/store/playlistFolderStore';
 import { groupPlaylistsByFolder } from '@/features/playlist/utils/playlistFolders';
-import { useDragDrop } from '@/contexts/DragDropContext';
+import { useDragDrop } from '@/lib/dnd/DragDropContext';
 import PlaylistFolderSection from '@/features/playlist/components/PlaylistFolderSection';
 
 interface Props {

src/features/playlist/hooks/usePlaylistDnDReorder.ts

@@ -1,6 +1,6 @@
 import React, { useEffect, useState } from 'react';
 import type { SubsonicSong } from '@/lib/api/subsonicTypes';
-import { useDragDrop } from '@/contexts/DragDropContext';
+import { useDragDrop } from '@/lib/dnd/DragDropContext';
 import { runPlaylistReorderDrop } from '@/features/playlist/utils/runPlaylistReorderDrop';
 
 export interface PlaylistDnDReorderDeps {

src/features/playlist/pages/PlaylistDetail.tsx

@@ -12,7 +12,7 @@ import { useAlbumOfflineState } from '@/features/album';
 import { useAuthStore } from '@/store/authStore';
 import { useDownloadModalStore } from '@/features/offline';
 import { useZipDownloadStore } from '@/features/offline';
-import { useDragDrop } from '@/contexts/DragDropContext';
+import { useDragDrop } from '@/lib/dnd/DragDropContext';
 import { useTranslation } from 'react-i18next';
 import type { SpotifyCsvTrack } from '@/features/playlist/utils/spotifyCsvImport';
 import { runPlaylistCsvImport } from '@/features/playlist/utils/runPlaylistCsvImport';

src/features/playlist/pages/Playlists.tsx

@@ -8,7 +8,7 @@ import { usePlayerStore } from '@/store/playerStore';
 import { usePlaylistStore } from '@/features/playlist/store/playlistStore';
 import { useAuthStore } from '@/store/authStore';
 import { useTranslation } from 'react-i18next';
-import { useRangeSelection } from '@/hooks/useRangeSelection';
+import { useRangeSelection } from '@/lib/hooks/useRangeSelection';
 
 import {
   defaultSmartFilters,

src/features/radio/components/RadioCard.tsx

@@ -3,7 +3,7 @@ import { useTranslation } from 'react-i18next';
 import { Cast, Globe, Heart, Square, Trash2, X } from 'lucide-react';
 import { open } from '@tauri-apps/plugin-shell';
 import type { InternetRadioStation } from '@/lib/api/subsonicTypes';
-import { useDragDrop, useDragSource } from '@/contexts/DragDropContext';
+import { useDragDrop, useDragSource } from '@/lib/dnd/DragDropContext';
 import { CoverArtImage } from '@/cover/CoverArtImage';
 import { albumCoverRef } from '@/cover/ref';
 import { coverArtIdFromRadio } from '@/cover/ids';

src/features/settings/components/BackdropSourceList.tsx

@@ -1,6 +1,6 @@
 import { useEffect, useRef, useState } from 'react';
 import { ChevronDown, ChevronUp, GripVertical } from 'lucide-react';
-import { useDragDrop, useDragSource } from '@/contexts/DragDropContext';
+import { useDragDrop, useDragSource } from '@/lib/dnd/DragDropContext';
 import type { BackdropSource, BackdropSourcePref } from '@/cover/artistBackdrop';
 import type { BackdropSurface } from '@/store/themeStore';
 import { moveSourceTo, dropSourceBefore } from '@/features/settings/components/backdropReorder';

src/features/settings/components/InputTab.tsx

@@ -1,7 +1,7 @@
 import { useState } from 'react';
 import { useTranslation } from 'react-i18next';
 import { Keyboard, RotateCcw, X } from 'lucide-react';
-import { IN_APP_SHORTCUT_ACTIONS, GLOBAL_SHORTCUT_ACTIONS } from '@/config/shortcutActions';
+import { IN_APP_SHORTCUT_ACTIONS, GLOBAL_SHORTCUT_ACTIONS } from '@/lib/shortcuts/shortcutActions';
 import { useGlobalShortcutsStore, type GlobalAction, buildGlobalShortcut, formatGlobalShortcut } from '@/store/globalShortcutsStore';
 import { useKeybindingsStore, type KeyAction, buildInAppBinding, formatBinding } from '@/store/keybindingsStore';
 import SettingsSubSection from '@/features/settings/components/SettingsSubSection';

src/features/settings/components/ReorderGripHandle.tsx

@@ -1,6 +1,6 @@
 import { useTranslation } from 'react-i18next';
 import { GripVertical } from 'lucide-react';
-import { useDragSource } from '@/contexts/DragDropContext';
+import { useDragSource } from '@/lib/dnd/DragDropContext';
 
 /**
  * Drag handle shared by the reorder customizers. Emits an id-based payload

src/features/settings/components/settingsSearch.ts

@@ -1,5 +1,5 @@
 import type { TFunction } from 'i18next';
-import { GLOBAL_SHORTCUT_ACTIONS, IN_APP_SHORTCUT_ACTIONS } from '@/config/shortcutActions';
+import { GLOBAL_SHORTCUT_ACTIONS, IN_APP_SHORTCUT_ACTIONS } from '@/lib/shortcuts/shortcutActions';
 import { SETTINGS_INDEX, matchScore, type Tab } from '@/features/settings/components/settingsTabs';
 
 export type SettingsSearchHit = {