Fix 8 code-review findings across transcode queue, requests, cleanup, music

- Episode transcode (single + bulk) now accepts storage_type=scan, matching
  stream_episode and the movie-transcode endpoint — Library-Scan-imported
  TV episodes can finally be transcoded, not just streamed.
- retry_job now forwards content_type, fixing retry for failed/cancelled
  episode jobs (was silently treating them as movies and failing again).
- cancel_job now updates the correct collection (movies vs episodes) based
  on content_type instead of always writing to db.movies.
- approve_request atomically claims the request (pending -> approving)
  before contacting Radarr/Sonarr, so a double-click or two concurrent
  admins can't both add the same content; releases the claim back to
  pending on any failure so a fixable error can be retried.
- Music enrichment's update_many now re-checks album_art_url is still
  empty, so it no longer clobbers art an admin manually set via PATCH.
- Library Cleanup's dangling-refs scan now also checks episode_progress
  for rows referencing a deleted episode (previously only watchlist/
  progress against movie_id were checked).
- Settings now surfaces a failed bulk-TMDB-enrich run as an error instead
  of a false "Enrichment done" success summary.
- Music player's isPlaying now syncs from the audio element's native
  play/pause events instead of only being set inside togglePlay/track-
  change, so it can't drift from actual playback state (buffering stalls,
  OS media-key pauses, etc).

frontend/src/lib/musicPlayer.jsx

@@ -41,29 +41,36 @@ export const MusicPlayerProvider = ({ children }) => {
     const audio = audioRef.current;
     if (!current) { audio.pause(); return; }
     audio.src = getTrackStreamUrl(current);
-    audio.play().then(() => setIsPlaying(true)).catch(() => setIsPlaying(false));
+    audio.play().catch(() => {}); // isPlaying reflects reality via the native play/pause listeners below
   }, [current]);
 
+  // isPlaying always mirrors the audio element's own state, so it stays correct through anything
+  // that changes playback outside togglePlay — a stall, an OS media-key pause, autoplay being blocked.
   useEffect(() => {
     const audio = audioRef.current;
     const onTime = () => setProgress({ position: audio.currentTime, duration: audio.duration || 0 });
     const onEnded = () => {
       if (index >= 0 && index < queue.length - 1) setIndex(index + 1);
-      else setIsPlaying(false);
     };
+    const onPlay = () => setIsPlaying(true);
+    const onPause = () => setIsPlaying(false);
     audio.addEventListener("timeupdate", onTime);
     audio.addEventListener("ended", onEnded);
+    audio.addEventListener("play", onPlay);
+    audio.addEventListener("pause", onPause);
     return () => {
       audio.removeEventListener("timeupdate", onTime);
       audio.removeEventListener("ended", onEnded);
+      audio.removeEventListener("play", onPlay);
+      audio.removeEventListener("pause", onPause);
     };
   }, [index, queue]);
 
   const togglePlay = useCallback(() => {
     const audio = audioRef.current;
     if (!current) return;
-    if (audio.paused) audio.play().then(() => setIsPlaying(true));
-    else { audio.pause(); setIsPlaying(false); }
+    if (audio.paused) audio.play().catch(() => {});
+    else audio.pause();
   }, [current]);
 
   const next = useCallback(() => {