refactor(lib): relocate the local-library subsystem utils/library -> lib/library

utils/library is the local-index query/browse/sync engine -- feature-free shared
infra consumed by the album, search, genre, artist and offline features. With
its last feature edges removed (queue resolver, shuffleArray, albumBrowseCatalogChunk,
genreBrowsePlayback all relocated earlier this branch), the whole directory is
pure infra and belongs under lib/.

Whole-directory move (58 files, 76 consumers rewritten) via resolver-based
rewrite: cross-cluster relatives absolutized to @/, intra-cluster siblings kept
relative. utils/library is gone; lib/library imports zero @/features. Three
stale doc comments in the album/search/artist barrels repointed.

tsc 0, lint 0, full suite 2353/2353, production build OK.

src/features/playback/store/playListenSession.test.ts

@@ -14,7 +14,7 @@ import {
 } from '@/features/playback/store/playListenSession';
 import { onPlaySessionRecorded } from '@/features/playback/store/playSessionRecorded';
 
-vi.mock('@/utils/library/libraryReady', () => ({
+vi.mock('@/lib/library/libraryReady', () => ({
   libraryIsReady: vi.fn(async () => true),
 }));
 
@@ -178,7 +178,7 @@ describe('playListenSession', () => {
   });
 
   it('skips when library is not ready', async () => {
-    const { libraryIsReady } = await import('@/utils/library/libraryReady');
+    const { libraryIsReady } = await import('@/lib/library/libraryReady');
     vi.mocked(libraryIsReady).mockResolvedValueOnce(false);
     vi.useFakeTimers();
     await playListenSessionOpen(testTrack, 'server-1');

src/features/playback/store/playListenSession.ts

@@ -5,7 +5,7 @@ import {
   libraryRecordPlaySession,
   type PlaySessionEndReason,
 } from '@/lib/api/library';
-import { libraryIsReady } from '@/utils/library/libraryReady';
+import { libraryIsReady } from '@/lib/library/libraryReady';
 import { getPlaybackServerId } from '@/features/playback/utils/playback/playbackServer';
 import { emitPlaySessionRecorded } from '@/features/playback/store/playSessionRecorded';
 import { useLibraryIndexStore } from '@/store/libraryIndexStore';

src/features/playback/store/queueTrackResolver.ts

@@ -5,8 +5,8 @@ import type { QueueItemRef, Track } from '@/features/playback/store/playerStoreT
 import { songToTrack } from '@/features/playback/utils/playback/songToTrack';
 import { resolveServerIdForIndexKey } from '@/utils/server/serverLookup';
 import { canonicalQueueServerKey } from '@/utils/server/serverIndexKey';
-import { trackToSong } from '@/utils/library/advancedSearchLocal';
-import { libraryIsReady } from '@/utils/library/libraryReady';
+import { trackToSong } from '@/lib/library/advancedSearchLocal';
+import { libraryIsReady } from '@/lib/library/libraryReady';
 
 /**
  * Queue track resolver (thin-state phase 2). Resolves `QueueItemRef`s to full