fix: correct artist names and prevent wrong song downloads for Japanese tracks

- spotify.js: stop overwriting trackName with iTunes English title —
  yt-dlp must search with original Japanese title to find the right song
  (was downloading English covers e.g. Ghost In A Flower instead of 幽霊花)
- metadata.js: add title-only fallback in lookupItunesTrackMeta so tracks
  are found even when kuromoji gives wrong artist romanization (e.g.
  Terui Jun Sei vs iTunes Yoshimasa Terui); also return itunesArtistName
- novasonic-server.js: use itunesArtistName from iTunes lookup as the
  stored artist when available (single-track and playlist download paths)

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

src/spotify.js

@@ -295,10 +295,8 @@ async function _loadSpotifyTrackArtwork(tracks, listEl) {
         if (match.trackExplicitness)  t.trackExplicitness  = match.trackExplicitness;
         if (match.previewUrl)         t.previewUrl         = match.previewUrl;
         if (match.trackTimeMillis)    t.durationMs         = match.trackTimeMillis;
-        // Use iTunes canonical English/romaji names — more accurate than Spotify (which may use Japanese)
-        if (match.artistName)         t.artistName         = match.artistName;
-        const JP_RE = /[぀-ヿ一-鿿]/;
-        if (JP_RE.test(t.trackName) && match.trackName) t.trackName = match.trackName;
+        // Use iTunes canonical English/romaji artist name (Spotify may have Japanese or wrong order)
+        if (match.artistName) t.artistName = match.artistName;
         if (window._spotifyResolved?.tracks?.[idx]) Object.assign(window._spotifyResolved.tracks[idx], t);
         const url = match.artworkUrl100 || match.artworkUrl60 || '';
         if (url) _setArt(artEls[idx], url);