fix(backend): strip release suffix from filename too (01 - Artist - Title)

The filename used the raw title, so "recognize - Single" leaked into the
filename ("01 - MINA - recognize - Single.mp3"). Now the cleaned title drives
both the filename and the embedded title tag, giving "01 - MINA - recognize.mp3"
(Track - Artist - Title). The album folder keeps the full album name.

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

backend/lib/ytdlp.js

@@ -77,11 +77,18 @@ async function downloadTrack({ jobId, artist, rawArtist, albumArtist, title, alb
     }
   }
 
+  // Strip release-type suffixes Spotify appends to track names (e.g. "recognize - Single" → "recognize").
+  // Only strip trailing "- word(s)" when those words are release-type qualifiers or bare years, not
+  // real sub-titles (which tend to be longer phrases or start with "feat"/"ft").
+  // Used for BOTH the filename ("01 - Artist - Title", no "- Single") and the YTM search query.
+  const RELEASE_SUFFIX_RE = /\s*[-–]\s*(?:(?:official\s+)?(?:music\s+)?(?:single|ep|lp|album|ost|soundtrack|remaster(?:ed)?|deluxe(?:\s+edition)?|bonus\s+tracks?|b-?sides?|version|edit)\b.*|(?:20|19)\d{2})\s*$/i;
+  const cleanTitle = title.replace(RELEASE_SUFFIX_RE, '').trim() || title;
+
   // Folder / filename: romaji of the resolved artist (iTunes name if available — already in English,
   // otherwise kuromoji). rawArtist (original Japanese) is only used for tags + YTM search.
   const mainArtistRomaji = romajiForStorage(mainArtist) || mainArtist;
   const artistRomaji     = romajiForStorage(artist)     || artist;
-  const titleRomaji      = romajiForStorage(title)      || title;
+  const titleRomaji      = romajiForStorage(cleanTitle) || cleanTitle;
   const albumRomaji      = album ? (romajiForStorage(album) || album) : null;
   const safeArtist = sanitize(mainArtistRomaji.split(/[,;&]/)[0].trim());
   const safeAlbum  = sanitize(albumRomaji || 'Singles');
@@ -110,11 +117,7 @@ async function downloadTrack({ jobId, artist, rawArtist, albumArtist, title, alb
 
   const escRe = s => s.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
 
-  // Strip release-type suffixes Spotify appends to track names (e.g. "recognize - Single" → "recognize").
+  const searchTitle = cleanTitle;
-  // Only strip trailing "- word(s)" when those words are release-type qualifiers or bare years, not
-  // real sub-titles (which tend to be longer phrases or start with "feat"/"ft").
-  const RELEASE_SUFFIX_RE = /\s*[-–]\s*(?:(?:official\s+)?(?:music\s+)?(?:single|ep|lp|album|ost|soundtrack|remaster(?:ed)?|deluxe(?:\s+edition)?|bonus\s+tracks?|b-?sides?|version|edit)\b.*|(?:20|19)\d{2})\s*$/i;
-  const searchTitle = title.replace(RELEASE_SUFFIX_RE, '').trim() || title;
 
   const variantFilter = buildVariantFilter(searchTitle);
   const titleKws      = buildTitleKeywords(searchTitle);