fix(backend): use space (not dash) between artist and title in search query

"MINA - recognize" skewed YTM ranking toward a same-named artist's full
discography, so the actual track (qNffDItRUeo) never appeared in results.
"MINA recognize" — matching how users type in the YTM search box — ranks
the exact official track first.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/lib/ytdlp.js

@@ -145,7 +145,10 @@ async function downloadTrack({ jobId, artist, rawArtist, albumArtist, title, alb
   // For Western tracks, artist + title + duration matching is sufficient (matches spotdl behaviour).
   const albumQuerySuffix = hasJpTitle && albumWords ? ' ' + albumWords : '';
 
-  const query = `${ytmArtist} - ${searchTitle}${albumQuerySuffix}`;
+  // Use a space (not " - ") between artist and title: this matches how users type
+  // in the YTM search box and ranks the exact official track first. A dash skews
+  // YTM ranking toward a same-named artist's full discography.
+  const query = `${ytmArtist} ${searchTitle}${albumQuerySuffix}`;
 
   const baseArgs = [
     '--extract-audio',
@@ -188,7 +191,7 @@ async function downloadTrack({ jobId, artist, rawArtist, albumArtist, title, alb
 
   const YTM_SONGS_PARAM = 'EgWKAQIIAWoKEAkQBRAKEAMQBA%3D%3D';
   // Use original (raw) artist for YTM URL — better ranking since channel is in original language
-  const ytmQuery = `${rawArtist || mainArtist} - ${searchTitle}${albumQuerySuffix}`;
+  const ytmQuery = `${rawArtist || mainArtist} ${searchTitle}${albumQuerySuffix}`;
   const ytmUrl = `https://music.youtube.com/search?q=${encodeURIComponent(ytmQuery)}&params=${YTM_SONGS_PARAM}`;
   const expectedAudio = path.join(dir, `${fileBase}.${CONFIG.audioFmt}`);
   const hasAudio = () => fs.existsSync(expectedAudio);