refactor(utils): group utils/ files into topic folders (Phase L, part 1) (#689)

111 of 122 top-level src/utils/ files move into 16 topic folders (audio,
cache, cover, share, server, playback, playlist, deviceSync, waveform,
mix, format, export, changelog, ui, perf, componentHelpers). True
singletons with no cluster stay at the utils/ root.

Pure file-move: a path-aware codemod rewrote 539 relative-import
specifiers across 275 files; no logic touched. The hot-path coverage
gate list (.github/frontend-hot-path-files.txt) is updated to the new
paths for the 11 gated utils files — a mechanical consequence of the
move, not a CI change. tsc is green.

src/utils/componentHelpers/runArtistDetailPlay.ts

@@ -0,0 +1,88 @@
+import type { TFunction } from 'i18next';
+import { getAlbum } from '../../api/subsonicLibrary';
+import { getSimilarSongs2, getTopSongs } from '../../api/subsonicArtists';
+import type { SubsonicAlbum, SubsonicArtist } from '../../api/subsonicTypes';
+import type { Track } from '../../store/playerStoreTypes';
+import { songToTrack } from '../playback/songToTrack';
+
+async function fetchAllTracks(albums: SubsonicAlbum[]): Promise<Track[]> {
+  const results = await Promise.all(albums.map(a => getAlbum(a.id)));
+  const sorted = [...results].sort((a, b) => (a.album.year ?? 0) - (b.album.year ?? 0));
+  return sorted.flatMap(r => [...r.songs].sort((a, b) => (a.track ?? 0) - (b.track ?? 0))).map(songToTrack);
+}
+
+export interface RunArtistDetailPlayDeps {
+  albums: SubsonicAlbum[];
+  setPlayAllLoading: (v: boolean) => void;
+  playTrack: (track: Track, queue: Track[]) => void;
+}
+
+export async function runArtistDetailPlayAll(deps: RunArtistDetailPlayDeps): Promise<void> {
+  const { albums, setPlayAllLoading, playTrack } = deps;
+  if (albums.length === 0) return;
+  setPlayAllLoading(true);
+  try {
+    const tracks = await fetchAllTracks(albums);
+    if (tracks.length > 0) playTrack(tracks[0], tracks);
+  } finally {
+    setPlayAllLoading(false);
+  }
+}
+
+export async function runArtistDetailShuffle(deps: RunArtistDetailPlayDeps): Promise<void> {
+  const { albums, setPlayAllLoading, playTrack } = deps;
+  if (albums.length === 0) return;
+  setPlayAllLoading(true);
+  try {
+    const tracks = await fetchAllTracks(albums);
+    if (tracks.length > 0) {
+      const shuffled = [...tracks].sort(() => Math.random() - 0.5);
+      playTrack(shuffled[0], shuffled);
+    }
+  } finally {
+    setPlayAllLoading(false);
+  }
+}
+
+export interface RunArtistDetailStartRadioDeps {
+  artist: SubsonicArtist;
+  t: TFunction;
+  setRadioLoading: (v: boolean) => void;
+  playTrack: (track: Track, queue: Track[]) => void;
+  enqueue: (tracks: Track[]) => void;
+}
+
+export async function runArtistDetailStartRadio(deps: RunArtistDetailStartRadioDeps): Promise<void> {
+  const { artist, t, setRadioLoading, playTrack, enqueue } = deps;
+  setRadioLoading(true);
+  try {
+    // Fire both fetches in parallel
+    const topPromise = getTopSongs(artist.name);
+    const similarPromise = getSimilarSongs2(artist.id, 50);
+
+    // Start playing as soon as top songs arrive
+    const top = await topPromise;
+    if (top.length > 0) {
+      const firstTrack = songToTrack(top[0]);
+      playTrack(firstTrack, [firstTrack]);
+      setRadioLoading(false);
+      // Enqueue remaining tracks when similar songs arrive
+      const similar = await similarPromise;
+      const remaining = [...top.slice(1), ...similar].map(songToTrack);
+      if (remaining.length > 0) enqueue(remaining);
+    } else {
+      // No top songs — fall back to similar
+      const similar = await similarPromise;
+      if (similar.length > 0) {
+        const tracks = similar.map(songToTrack);
+        playTrack(tracks[0], tracks);
+      } else {
+        alert(t('artistDetail.noRadio'));
+      }
+      setRadioLoading(false);
+    }
+  } catch (e) {
+    console.error('Radio start failed', e);
+    setRadioLoading(false);
+  }
+}