refactor(utils): split componentHelpers grab-bag to owning layers

Per-file routing of the 9-file utils/componentHelpers grab-bag, each driven by
its verified consumer set:
- contextMenu{Actions,Helpers} → features/contextMenu/utils (sole consumer)
- queuePanelHelpers → features/queue/utils (sole consumer)
- nowPlayingHelpers → features/nowPlaying/utils; isRealArtistImage split out to
  cover/ (consumed by cover/artistHero, a lower layer)
- appUpdaterHelpers(+test) + listReorder(+test) → lib/util (config/ + lib/hooks
  consume them; pure)
- playlistDetailHelpers → lib/format (consumed by 3 features; pure)
- appShellHelpers → app/ (app-shell consumers only)
- userMgmtHelpers left in place: consumed by the a11y-HELD SongInfoModal, so a
  move would rewrite a do-not-touch file (same block as licensesData).

Pure moves; tests pass unmodified.

src/features/queue/components/QueueCurrentTrack.tsx

@@ -7,7 +7,7 @@ import type { PlaybackSourceKind } from '@/features/playback/utils/playback/reso
 import {
   formatQueueReplayGainParts,
   renderStars,
-} from '@/utils/componentHelpers/queuePanelHelpers';
+} from '@/features/queue/utils/queuePanelHelpers';
 import { loudnessGainPlaceholderUntilCacheDb } from '@/features/playback/utils/audio/loudnessPlaceholder';
 import { effectiveLoudnessPreAnalysisAttenuationDb } from '@/lib/audio/loudnessPreAnalysisSlider';
 import { formatQueueBpmTech, formatQueueMoodLabels } from '@/lib/library/trackEnrichment';

src/features/queue/components/QueueHeader.tsx

@@ -6,7 +6,7 @@ import { usePlayerStore } from '@/features/playback/store/playerStore';
 import { useAuthStore } from '@/store/authStore';
 import type { QueueItemRef } from '@/lib/media/trackTypes';
 import type { QueueDisplayMode } from '@/store/authStoreTypes';
-import type { DurationMode } from '@/utils/componentHelpers/queuePanelHelpers';
+import type { DurationMode } from '@/features/queue/utils/queuePanelHelpers';
 import { formatLongDuration } from '@/lib/format/formatDuration';
 import { formatClockTime } from '@/lib/format/formatClockTime';
 import { resolveQueueTrack } from '@/features/playback/store/queueTrackView';

src/features/queue/utils/queuePanelHelpers.tsx

@@ -0,0 +1,36 @@
+import { Star } from 'lucide-react';
+import type { TFunction } from 'i18next';
+import type { Track } from '@/lib/media/trackTypes';
+
+export type { DurationMode } from '@/store/authStoreTypes';
+
+export function formatQueueReplayGainParts(track: Track, t: TFunction): string[] {
+  const parts: string[] = [];
+  const fmtDb = (db: number) => `${db >= 0 ? '+' : ''}${db.toFixed(1)}`;
+  if (track.replayGainTrackDb != null) {
+    parts.push(t('queue.rgTrack', { db: fmtDb(track.replayGainTrackDb) }));
+  }
+  if (track.replayGainAlbumDb != null) {
+    parts.push(t('queue.rgAlbum', { db: fmtDb(track.replayGainAlbumDb) }));
+  }
+  if (track.replayGainPeak != null) {
+    parts.push(t('queue.rgPeak', { pk: track.replayGainPeak.toFixed(3) }));
+  }
+  return parts;
+}
+
+export function renderStars(rating?: number) {
+  if (!rating) return null;
+  const stars = [];
+  for (let i = 1; i <= 5; i++) {
+    stars.push(
+      <Star
+        key={i}
+        size={12}
+        fill={i <= rating ? 'var(--highlight)' : 'none'}
+        color={i <= rating ? 'var(--highlight)' : 'var(--text-muted)'}
+      />
+    );
+  }
+  return <div style={{ display: 'flex', gap: '2px', alignItems: 'center' }}>{stars}</div>;
+}