refactor(api): F.49 — extract library + artists + ratings (#614)

Three domain-eng modules peel ~316 LOC of fetch/mapping out of
`api/subsonic.ts`:

- `subsonicLibrary.ts` — browse + random + per-song fetch
  (`getMusicDirectory`, `getMusicIndexes`, `getMusicFolders`,
  `getRandomAlbums`, `getAlbumList`, `getRandomSongs`,
  `getRandomSongsFiltered`, `getSong`, `getAlbum`,
  `filterSongsToActiveLibrary`, `similarSongsRequestCount`, plus
  the private `albumIdsInActiveLibraryScope` cache).
- `subsonicArtists.ts` — artist endpoints (`getArtists`, `getArtist`,
  `getArtistInfo`, `getTopSongs`, `getSimilarSongs2`,
  `getSimilarSongs`). Uses Library's `filterSongsToActiveLibrary` and
  `similarSongsRequestCount` for the per-library scoping fallback.
- `subsonicRatings.ts` — `parseSubsonicEntityStarRating` parser plus
  `prefetchArtistUserRatings` and `prefetchAlbumUserRatings` workers
  with the shared 7-min cache. Calls back into Library/Artists for
  the per-id fetch.

51 external call sites migrated to direct imports. No re-export
shims in `subsonic.ts`. Statistics endpoints still in `subsonic.ts`
keep their `RATING_CACHE_TTL` constant locally (same 7-min window).

subsonic.ts: 1078 → 762 LOC (−316).

src/utils/applySharePaste.ts

@@ -1,8 +1,9 @@
+import { getArtist } from '../api/subsonicArtists';
+import { getAlbum, getSong } from '../api/subsonicLibrary';
 import type { SubsonicSong } from '../api/subsonicTypes';
 import { songToTrack } from '../utils/songToTrack';
 import type { NavigateFunction } from 'react-router-dom';
 import type { TFunction } from 'i18next';
-import { getAlbum, getArtist, getSong } from '../api/subsonic';
 import { useAuthStore } from '../store/authStore';
 import { usePlayerStore } from '../store/playerStore';
 import { findServerIdForShareUrl, type EntitySharePayloadV1 } from './shareLink';

src/utils/buildInfiniteQueueCandidates.test.ts

@@ -6,12 +6,17 @@
  * refactor (2026-05-12). This test pins the artist-first / random-fallback
  * order, the dedup contract against existingIds, and the autoAdded flag.
  */
+import { getSimilarSongs2, getTopSongs } from '../api/subsonicArtists';
+import { getRandomSongs } from '../api/subsonicLibrary';
 import type { Track } from '../store/playerStoreTypes';
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 
-vi.mock('../api/subsonic', () => ({
+vi.mock('../api/subsonicArtists', () => ({
   getSimilarSongs2: vi.fn(),
   getTopSongs: vi.fn(),
+}));
+
+vi.mock('../api/subsonicLibrary', () => ({
   getRandomSongs: vi.fn(),
 }));
 
@@ -22,7 +27,6 @@ vi.mock('./mixRatingFilter', () => ({
 }));
 
 import { buildInfiniteQueueCandidates } from './buildInfiniteQueueCandidates';
-import { getRandomSongs, getSimilarSongs2, getTopSongs } from '../api/subsonic';
 import {
   enrichSongsForMixRatingFilter,
   getMixMinRatingsConfigFromAuth,

src/utils/buildInfiniteQueueCandidates.ts

@@ -1,5 +1,6 @@
+import { getSimilarSongs2, getTopSongs } from '../api/subsonicArtists';
+import { getRandomSongs } from '../api/subsonicLibrary';
 import type { Track } from '../store/playerStoreTypes';
-import { getRandomSongs, getSimilarSongs2, getTopSongs } from '../api/subsonic';
 import {
   enrichSongsForMixRatingFilter,
   getMixMinRatingsConfigFromAuth,

src/utils/exportNewAlbums.ts

@@ -1,7 +1,8 @@
+import { getAlbumList } from '../api/subsonicLibrary';
 import type { SubsonicAlbum } from '../api/subsonicTypes';
 import { writeFile } from '@tauri-apps/plugin-fs';
 import { downloadDir, join } from '@tauri-apps/api/path';
-import { getAlbumList, buildCoverArtUrl } from '../api/subsonic';
+import { buildCoverArtUrl } from '../api/subsonic';
 import { useAuthStore } from '../store/authStore';
 // Catppuccin Macchiato palette
 const M = {

src/utils/luckyMix.ts

@@ -1,7 +1,8 @@
+import { getSimilarSongs, getTopSongs } from '../api/subsonicArtists';
+import { filterSongsToActiveLibrary, getAlbum, getAlbumList, getRandomSongs } from '../api/subsonicLibrary';
 import type { SubsonicAlbum, SubsonicSong } from '../api/subsonicTypes';
 import type { Track } from '../store/playerStoreTypes';
 import { songToTrack } from '../utils/songToTrack';
-import { filterSongsToActiveLibrary, getAlbum, getAlbumList, getRandomSongs, getSimilarSongs, getTopSongs } from '../api/subsonic';
 import { invoke } from '@tauri-apps/api/core';
 import i18n from '../i18n';
 import { useAuthStore } from '../store/authStore';

src/utils/mixRatingFilter.ts

@@ -1,5 +1,6 @@
+import { parseSubsonicEntityStarRating, prefetchAlbumUserRatings, prefetchArtistUserRatings } from '../api/subsonicRatings';
+import { getRandomSongs } from '../api/subsonicLibrary';
 import type { SubsonicAlbum, SubsonicSong } from '../api/subsonicTypes';
-import { getRandomSongs, parseSubsonicEntityStarRating, prefetchAlbumUserRatings, prefetchArtistUserRatings } from '../api/subsonic';
 import { useAuthStore } from '../store/authStore';
 
 /** Default target list size for Random Mix; per-call override via `fetchRandomMixSongsUntilFull(c, { targetSize })`. */

src/utils/orbit.ts

@@ -1,13 +1,6 @@
+import { getSong } from '../api/subsonicLibrary';
 import { songToTrack } from '../utils/songToTrack';
-import {
-  createPlaylist,
-  updatePlaylist,
-  updatePlaylistMeta,
-  deletePlaylist,
-  getPlaylist,
-  getPlaylists,
-  getSong,
-} from '../api/subsonic';
+import { createPlaylist, updatePlaylist, updatePlaylistMeta, deletePlaylist, getPlaylist, getPlaylists } from '../api/subsonic';
 import { useAuthStore } from '../store/authStore';
 import { useOrbitStore } from '../store/orbitStore';
 import { usePlayerStore } from '../store/playerStore';

src/utils/playAlbum.ts

@@ -1,4 +1,4 @@
-import { getAlbum } from '../api/subsonic';
+import { getAlbum } from '../api/subsonicLibrary';
 import { usePlayerStore } from '../store/playerStore';
 import { songToTrack } from './songToTrack';
 import { useOrbitStore } from '../store/orbitStore';

src/utils/playArtistShuffled.ts

@@ -1,6 +1,7 @@
+import { getArtist } from '../api/subsonicArtists';
+import { getAlbum } from '../api/subsonicLibrary';
 import { songToTrack } from '../utils/songToTrack';
 import { shuffleArray } from '../utils/shuffleArray';
-import { getAlbum, getArtist } from '../api/subsonic';
 import { usePlayerStore } from '../store/playerStore';
 /**
  * All tracks from the artist’s albums, shuffled — same idea as Artist page “shuffle play”.

src/utils/playByOpaqueId.ts

@@ -1,5 +1,5 @@
+import { getAlbum, getSong } from '../api/subsonicLibrary';
 import { songToTrack } from '../utils/songToTrack';
-import { getAlbum, getSong } from '../api/subsonic';
 import { playAlbum } from './playAlbum';
 import { playArtistShuffled } from './playArtistShuffled';
 import { usePlayerStore } from '../store/playerStore';