refactor(lib): consolidate generic infra into src/lib

Move domain-agnostic, feature-free helpers out of the flat utils/ and store/
roots into src/lib/ (plan M4, §3 lib/ layer):
- lib/format/: formatBytes, formatClockTime, formatDuration, formatHumanDuration,
  relativeTime (pure format/date/byte/clock helpers)
- lib/i18n.ts: i18next bootstrap (global app infra)
- lib/util/: sanitizeHtml, platform, dedupeById, safeStorage (pure helpers +
  the zustand storage adapter)

playbackScheduleFormat stays in utils/format (runtime usePlayerStore dep =
audio-core coupling, not generic). formatClockTime keeps a type-only
@/store/authStoreTypes import (erased, no runtime inversion — accepted per the
deviceSync precedent).

Pure move via deep @/lib/* specifiers (no barrel → no mock-collapse surface).
tsc 0, lint 0/0, full suite 319 files / 2353 tests green.

Tooling note: lib_move.py regex extended to also rewrite side-effect imports
(import './i18n') and vi.importActual paths — both were silent gaps.

src/features/offline/utils/favoritesOfflineSync.ts

@@ -6,7 +6,7 @@ import { getStarredForServer } from '@/lib/api/subsonicStarRating';
 import { buildStreamUrlForServer } from '@/lib/api/subsonicStreamUrl';
 import type { SubsonicSong } from '@/lib/api/subsonicTypes';
 import { invoke } from '@tauri-apps/api/core';
-import i18n from '@/i18n';
+import i18n from '@/lib/i18n';
 import { useAuthStore } from '@/store/authStore';
 import { cancelledDownloads, useOfflineJobStore } from '@/features/offline/store/offlineJobStore';
 import { useFavoritesOfflineSyncStore } from '@/features/offline/store/favoritesOfflineSyncStore';

src/features/offline/utils/offlineStarredLoad.ts

@@ -11,7 +11,7 @@ import {
   albumToAlbum,
   trackToSong,
 } from '@/utils/library/advancedSearchLocal';
-import { dedupeById } from '@/utils/dedupeById';
+import { dedupeById } from '@/lib/util/dedupeById';
 import { isOfflineBrowseActive } from '@/features/offline/utils/offlineBrowseMode';
 import { favoritesServerIds } from '@/features/offline/utils/favoritesOfflineBrowse';
 import {