refactor(lib,playback): relocate albumDetailNavigation + mixRatingFilter decouple-knots

Two lower-layer→feature inversions removed:

- Detail-route predicates (isAlbumDetailPath/isArtistDetailPath/isComposerDetailPath)
  were defined in features/album's browse store but are pure URL checks. Extracted
  to lib/navigation/detailRoutePaths; the browse store re-exports them so the
  @/features/album barrel surface is unchanged. This frees albumDetailNavigation of
  its only @/features import, so it moves utils/navigation → lib/navigation (drains
  utils/navigation). Also fixes the M5 isArtistDetailPath misplacement.

- mixRatingFilter's sole feature dep is playback's userRatingOverrides and its only
  binding consumer is playback's buildInfiniteQueueCandidates, so it belongs in the
  playback feature: utils/mix → features/playback/utils (drains utils/mix). The
  earlier handoff note that lib/api/subsonicStarRating consumes it was stale — that
  is only a code comment, verified no runtime import.

Pure moves; tests pass unmodified. The share cluster + switchActiveServer stay in
utils/ — they are imported by the a11y-HELD PasteClipboardHandler, so relocating
them would rewrite a do-not-touch file.

src/features/contextMenu/utils/contextMenuActions.ts

@@ -1,7 +1,7 @@
 import { join } from '@tauri-apps/api/path';
 import { invoke } from '@tauri-apps/api/core';
 import { getSimilarSongs2, fetchSimilarTracksRouted, getTopSongs } from '@/lib/api/subsonicArtists';
-import { filterSongsForLuckyMixRatings, getMixMinRatingsConfigFromAuth } from '@/utils/mix/mixRatingFilter';
+import { filterSongsForLuckyMixRatings, getMixMinRatingsConfigFromAuth } from '@/features/playback/utils/mixRatingFilter';
 import { buildDownloadUrl } from '@/lib/api/subsonicStreamUrl';
 import { useAuthStore } from '@/store/authStore';
 import { usePlayerStore } from '@/features/playback/store/playerStore';