fix(backend): strip release suffix from title metadata tag

searchTitle (e.g. "recognize") is now passed to embedMetadata instead of
the raw title ("recognize - Single"), so the ID3 title tag matches the
actual song name. Album tag stays unchanged ("recognize - Single").

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/lib/ytdlp.js

@@ -195,7 +195,7 @@ async function downloadTrack({ jobId, artist, rawArtist, albumArtist, title, alb
     await spawnYtdlp([sourceUrl, '--no-playlist', ...baseArgs]);
     const audioFile = hasAudio() ? expectedAudio : null;
     if (!audioFile) { log(jobId, '⚠️  Download fehlgeschlagen'); return { success: true, dir }; }
-    return embedMetadata({ jobId, audioFile, dir, trackPrefix, safeTitle, rawArtist, artist, mainArtist, album, year, trackNum, totalTracks, discNum, discTotal, compilation, genre, artworkUrl, explicit, title });
+    return embedMetadata({ jobId, audioFile, dir, trackPrefix, safeTitle, rawArtist, artist, mainArtist, album, year, trackNum, totalTracks, discNum, discTotal, compilation, genre, artworkUrl, explicit, title: searchTitle });
   }
 
   // Fetch YTM search result URLs as a flat list (no channel expansion) and return only
@@ -346,7 +346,7 @@ async function downloadTrack({ jobId, artist, rawArtist, albumArtist, title, alb
     return { success: true, dir };
   }
 
-  return embedMetadata({ jobId, audioFile, dir, trackPrefix, safeTitle, rawArtist, artist, mainArtist, album, year, trackNum, totalTracks, discNum, discTotal, compilation, genre, artworkUrl, explicit, title });
+  return embedMetadata({ jobId, audioFile, dir, trackPrefix, safeTitle, rawArtist, artist, mainArtist, album, year, trackNum, totalTracks, discNum, discTotal, compilation, genre, artworkUrl, explicit, title: searchTitle });
 }
 
 // Shared ffmpeg metadata embedding — used by both yt-dlp and squid paths