fix: repair Japanese song download pipeline

Five separate root causes fixed:

1. buildTitleKeywords (ytdlp.js): For Japanese titles \w strips all
   kana/kanji leaving no keywords. Now uses the first whitespace-
   delimited segment as a literal regex keyword so --match-filter
   title ~= requires the YTM video to contain the Japanese text.

2. Tokenizer wait (ytdlp.js): If kuromoji hasn't finished loading when
   a Japanese download starts, romajiForStorage returns the original
   Japanese text unchanged — producing Japanese folder/filenames and
   skipping sort tags. Now waits up to 30 s for the tokenizer.

3. titleOnlyMatch guard (metadata.js): iTunes titleOnlyMatch (no artist
   check) was used as a fallback for all searches. For Japanese
   titles/artists this matched wrong US songs with identical titles
   (common in anime OSTs). Now titleOnlyMatch is skipped when the
   search title or artist contains Japanese characters.

4. squid.js rawArtist: rawArtist was not in squid's signature and
   never forwarded to embedMetadata, so Qobuz-downloaded J-Pop tracks
   stored the iTunes-resolved English name as artist instead of the
   Japanese original. Fixed by accepting and forwarding rawArtist.

5. squid.js romaji paths: Folder and filename used raw artist/title
   with no romaji conversion, creating Japanese-named paths
   inconsistent with the yt-dlp path. Now uses romajiForStorage same
   as ytdlp.js.

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

backend/lib/squid.js

@@ -11,6 +11,7 @@ const {
   downloadArtwork, fetchLyrics, findExistingTrack,
 } = require('./metadata');
 const { embedMetadata } = require('./ytdlp');
+const { romajiForStorage } = require('./romaji');
 
 const SQUID_BASE = 'https://qobuz.squid.wtf';
 
@@ -222,14 +223,18 @@ async function downloadUrlToFile(url, destPath) {
 
 // Download a single track via squid.wtf / Qobuz.
 // Returns { success: true, dir, skipped? } on success, null if track not found on Qobuz.
-async function downloadTrack({ jobId, artist, albumArtist, title, album, year, trackNum, totalTracks, discNum, discTotal, compilation, genre, artworkUrl, explicit, outputDir, durationMs }) {
+async function downloadTrack({ jobId, artist, rawArtist, albumArtist, title, album, year, trackNum, totalTracks, discNum, discTotal, compilation, genre, artworkUrl, explicit, outputDir, durationMs }) {
   const mainArtist = albumArtist || artist;
-  const safeArtist = sanitize(mainArtist.split(',')[0].trim());
-  const safeAlbum  = sanitize(album || 'Singles');
+  // Use romaji for folder/filename — same as ytdlp path so paths are consistent
+  const mainArtistRomaji = romajiForStorage(mainArtist) || mainArtist;
+  const titleRomaji      = romajiForStorage(title)      || title;
+  const albumRomaji      = album ? (romajiForStorage(album) || album) : null;
+  const safeArtist = sanitize(mainArtistRomaji.split(/[,;&]/)[0].trim());
+  const safeAlbum  = sanitize(albumRomaji || 'Singles');
   const dir        = path.join(outputDir || CONFIG.musicPath, safeArtist, safeAlbum);
   fs.mkdirSync(dir, { recursive: true });
 
-  const safeTitle   = sanitize(title);
+  const safeTitle   = sanitize(titleRomaji);
   const trackPrefix = trackNum ? String(trackNum).padStart(2, '0') + ' - ' : '';
   const ext         = squidExt();
 
@@ -278,7 +283,7 @@ async function downloadTrack({ jobId, artist, albumArtist, title, album, year, t
 
   return embedMetadata({
     jobId, audioFile, dir, trackPrefix, safeTitle,
-    artist, mainArtist, album, year, trackNum, totalTracks,
+    rawArtist, artist, mainArtist, album, year, trackNum, totalTracks,
     discNum, discTotal, compilation, genre,
     artworkUrl: finalArtwork, explicit, title,
   });