refactor(api): co-locate server-protocol clients into lib/api

Move the Subsonic + Navidrome protocol clients and the library IPC facade
(subsonic*, navidrome*, library.ts + tests) from src/api/ into src/lib/api/,
the feature-free infra layer (plan M4, decision §10.3: shared client core → lib/).
Pure move: deep-path import specifiers @/api/* -> @/lib/api/* across ~150
consumers; no behaviour change. Domain REST (lyrics/events) and cover/analysis
infra stay in src/api/ pending their own M4 placement.

tsc 0, lint 0/0, full suite 319 files / 2353 tests green.

src/cover/TrackCoverArtImage.tsx

@@ -1,4 +1,4 @@
-import type { SubsonicSong } from '../api/subsonicTypes';
+import type { SubsonicSong } from '@/lib/api/subsonicTypes';
 import { CoverArtImage, type CoverArtImageProps } from './CoverArtImage';
 import { useTrackCoverRef } from './useLibraryCoverRef';
 import { COVER_SCOPE_ACTIVE, type CoverServerScope } from './types';

src/cover/artistHero.tsx

@@ -1,5 +1,5 @@
 import { useEffect, useMemo, useState, type CSSProperties, type ImgHTMLAttributes } from 'react';
-import type { SubsonicArtistInfo } from '../api/subsonicTypes';
+import type { SubsonicArtistInfo } from '@/lib/api/subsonicTypes';
 import { isRealArtistImage } from '../utils/componentHelpers/nowPlayingHelpers';
 import { CoverArtImage } from './CoverArtImage';
 import type { CoverArtRef, CoverSurfaceKind } from './types';

src/cover/fetchUrl.ts

@@ -1,7 +1,7 @@
 import {
   buildCoverArtUrl,
   buildCoverArtUrlForServer,
-} from '../api/subsonicStreamUrl';
+} from '@/lib/api/subsonicStreamUrl';
 import { getPlaybackServerId } from '../utils/playback/playbackServer';
 import { useAuthStore } from '../store/authStore';
 import { connectBaseUrlForServer } from '../utils/server/serverEndpoint';

src/cover/integrations/discord.ts

@@ -1,4 +1,4 @@
-import { buildCoverArtUrlForServer } from '../../api/subsonicStreamUrl';
+import { buildCoverArtUrlForServer } from '@/lib/api/subsonicStreamUrl';
 import { serverShareBaseUrl } from '../../utils/server/serverEndpoint';
 import { useAuthStore } from '../../store/authStore';
 import type { CoverArtRef } from '../types';

src/cover/ref.ts

@@ -1,7 +1,7 @@
 import { getPlaybackServerId } from '../utils/playback/playbackServer';
 import { useAuthStore } from '../store/authStore';
 import { coverServerScopeForServerId } from './serverScope';
-import type { SubsonicSong } from '../api/subsonicTypes';
+import type { SubsonicSong } from '@/lib/api/subsonicTypes';
 import type { CoverArtId, CoverArtRef, CoverCacheKind, CoverServerScope } from './types';
 import {
   albumHasDistinctDiscCovers,

src/cover/resolveEntry.ts

@@ -8,7 +8,7 @@
  * stay in sync with `resolve_album_cover` / `resolve_artist_cover` there.
  */
 
-import type { SubsonicAlbum, SubsonicSong } from '../api/subsonicTypes';
+import type { SubsonicAlbum, SubsonicSong } from '@/lib/api/subsonicTypes';
 import type { CoverArtRef, CoverCacheKind, CoverServerScope } from './types';
 
 /** Resolved cover identity — maps 1:1 to Rust `CoverEntry`. */

src/cover/useLibraryCoverPrefetch.ts

@@ -1,5 +1,5 @@
 import { useEffect } from 'react';
-import type { SubsonicSong } from '../api/subsonicTypes';
+import type { SubsonicSong } from '@/lib/api/subsonicTypes';
 import { coverPrefetchRegister } from './prefetchRegistry';
 import {
   resolveAlbumCoverRefsFromLibrary,

src/cover/useLibraryCoverRef.ts

@@ -1,5 +1,5 @@
 import { useEffect, useMemo, useState, type Dispatch, type SetStateAction } from 'react';
-import type { SubsonicSong } from '../api/subsonicTypes';
+import type { SubsonicSong } from '@/lib/api/subsonicTypes';
 import { useAuthStore } from '../store/authStore';
 import { usePlayerStore } from '../store/playerStore';
 import {

src/cover/warmDiskPeek.ts

@@ -1,5 +1,5 @@
 import { coverCachePeekBatch } from '../api/coverCache';
-import type { SubsonicAlbum } from '../api/subsonicTypes';
+import type { SubsonicAlbum } from '@/lib/api/subsonicTypes';
 import { coverEnsureQueued, ensureArtistBackdropQueued } from './ensureQueue';
 import { getDiskSrcForGrid, rememberGridDiskSrc } from './diskSrcLookup';
 import { albumCoverRef, artistCoverRef } from './ref';