fix: romaji for album names + Japanese playlist track matching

- ytdlp.js + novasonic-server.js: apply romajiForStorage to album tag
  and folder/rename paths (was only applied to artist/title before)
- ui.js: _createNdPlaylist falls back to romaji index for Japanese titles
  since Navidrome search3 doesn't index Japanese text properly

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

backend/lib/ytdlp.js

@@ -53,8 +53,9 @@ async function downloadTrack({ jobId, artist, albumArtist, title, album, year, t
   const mainArtistRomaji = romajiForStorage(mainArtist) || mainArtist;
   const artistRomaji     = romajiForStorage(artist)     || artist;
   const titleRomaji      = romajiForStorage(title)      || title;
+  const albumRomaji      = album ? (romajiForStorage(album) || album) : null;
   const safeArtist = sanitize(mainArtistRomaji.split(/[,;&]/)[0].trim());
-  const safeAlbum  = sanitize(album || 'Singles');
+  const safeAlbum  = sanitize(albumRomaji || 'Singles');
   const dir = path.join(outputDir || CONFIG.musicPath, safeArtist, safeAlbum);
   fs.mkdirSync(dir, { recursive: true });
 
@@ -306,6 +307,7 @@ async function embedMetadata({ jobId, audioFile, dir, trackPrefix, safeTitle, ar
     const storedTitle       = romajiForStorage(title)                                       || title;
     const storedArtist      = romajiForStorage(navidromeArtist(artist))                    || navidromeArtist(artist);
     const storedAlbumArtist = romajiForStorage(mainArtist.replace(/\s+&\s+/g, ', '))       || mainArtist.replace(/\s+&\s+/g, ', ');
+    const storedAlbum       = album ? (romajiForStorage(album) || album) : null;
     ffArgs.push(
       '-c',             'copy',
       '-map_metadata',  '-1',
@@ -314,7 +316,7 @@ async function embedMetadata({ jobId, audioFile, dir, trackPrefix, safeTitle, ar
       '-metadata', `artist=${storedArtist}`,
       '-metadata', `album_artist=${storedAlbumArtist}`,
     );
-    if (album)       ffArgs.push('-metadata', `album=${album}`);
+    if (storedAlbum) ffArgs.push('-metadata', `album=${storedAlbum}`);
     if (year)        ffArgs.push('-metadata', `date=${String(year)}`);
     if (trackNum)    ffArgs.push('-metadata', `track=${totalTracks ? `${trackNum}/${totalTracks}` : String(trackNum)}`);
     if (totalTracks) ffArgs.push('-metadata', `totaltracks=${String(totalTracks)}`);