feat: batch fix artist sort tags + rename folder when override is added

- edit-metadata: use albumArtistSort (when provided) for artist folder naming
  instead of auto-converted romajiAlbumArtist — ensures manual overrides sent
  by the download pipeline also place files in the correct folder
- Add POST /api/fix-artist-sort endpoint: searches Navidrome for all songs
  where artist or albumArtist matches the kanji, re-writes ARTISTSORT +
  ALBUMARTISTSORT via ffmpeg (-map_metadata 0 preserves all other existing
  tags), moves each file to the correct artist folder, cleans up empty old
  dirs, triggers Navidrome rescan — returns a job ID for progress tracking
- addRomajiOverrideUI: after saving a new override, calls fix-artist-sort and
  shows a job card with live progress

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

backend/novasonic-server.js

@@ -602,6 +602,130 @@ app.post('/api/download', async (req, res) => {
   });
 });
 
+// POST /api/fix-artist-sort — batch-update sort tags + rename artist folder for all songs by a kanji artist
+app.post('/api/fix-artist-sort', async (req, res) => {
+  const { ndUrl, user, pass, artistKanji, artistSort, jobId: clientJobId } = req.body;
+  if (!ndUrl || !user || !pass || !artistKanji || !artistSort)
+    return res.status(400).json({ error: 'ndUrl, user, pass, artistKanji, artistSort required' });
+
+  const jobId = clientJobId || ('job_' + Date.now());
+  jobs.set(jobId, {
+    id: jobId, type: 'fix-sort',
+    artist: artistKanji, title: `Romaji-Fix: ${artistSort}`, album: '',
+    status: 'queued', progress: 0, message: 'Suche Songs…',
+    log: [], createdAt: Date.now(), updatedAt: Date.now(),
+  });
+  res.json({ jobId, status: 'queued' });
+
+  (async () => {
+    const mkTok = () => {
+      const s = Math.random().toString(36).slice(2, 10);
+      return { s, t: crypto.createHash('md5').update(pass + s).digest('hex') };
+    };
+
+    // Search Navidrome for all songs by this artist
+    let songs = [];
+    try {
+      const { s, t } = mkTok();
+      const r = await fetch(
+        `${ndUrl}/rest/search3?query=${encodeURIComponent(artistKanji)}&artistCount=0&albumCount=0&songCount=500&u=${encodeURIComponent(user)}&t=${t}&s=${s}&v=1.16.1&c=novasonic&f=json`,
+        { signal: AbortSignal.timeout(15000) }
+      );
+      const d = await r.json();
+      const all = d?.['subsonic-response']?.searchResult3?.song || [];
+      songs = all.filter(sng => sng.artist === artistKanji || sng.albumArtist === artistKanji);
+    } catch (e) {
+      updateJob(jobId, { status: 'error', message: `Navidrome-Suche fehlgeschlagen: ${e.message}` });
+      return;
+    }
+
+    if (!songs.length) {
+      updateJob(jobId, { status: 'done', progress: 100, message: 'Keine Songs gefunden' });
+      return;
+    }
+
+    log(jobId, `🔍 ${songs.length} Songs gefunden für "${artistKanji}"`);
+    updateJob(jobId, { status: 'running', progress: 10, message: `${songs.length} Songs gefunden…` });
+
+    let done = 0, errors = 0;
+    const safeArtistDir = sanitize(artistSort.split(/[,;&]/)[0].trim());
+
+    for (const ndSong of songs) {
+      try {
+        // Resolve file path
+        let filePath = ndSong.path;
+        if (!filePath) { errors++; continue; }
+        if (!path.isAbsolute(filePath)) filePath = path.join(CONFIG.musicPath, filePath);
+        if (!fs.existsSync(filePath)) {
+          const fileName  = path.basename(filePath);
+          const titleStem = fileName.replace(AUDIO_EXT_RE, '').replace(/^\d+\s*-\s*/, '').toLowerCase();
+          const found = _rebasePath(filePath, CONFIG.musicPath)
+            || _findFileRecursive(CONFIG.musicPath, fileName)
+            || _findFileByStemOrRomaji(CONFIG.musicPath, titleStem);
+          if (found) filePath = found;
+          else { log(jobId, `⚠ Nicht gefunden: ${path.basename(ndSong.path || '')}`); errors++; continue; }
+        }
+
+        const fileExt = path.extname(filePath);
+        const tmpFile = filePath.slice(0, -fileExt.length) + '.sorttmp' + fileExt;
+
+        // -map_metadata 0 preserves all existing tags; individual -metadata flags override only sort ones
+        await new Promise((resolve, reject) => {
+          const ff = spawn('ffmpeg', [
+            '-i', filePath,
+            '-map', '0:a', '-map', '0:v?',
+            '-c', 'copy', '-map_metadata', '0',
+            '-metadata', `ARTISTSORT=${artistSort}`,
+            '-metadata', `ALBUMARTISTSORT=${artistSort}`,
+            tmpFile, '-y', '-loglevel', 'error',
+          ]);
+          let ffErr = '';
+          ff.stderr.on('data', d => ffErr += d.toString());
+          ff.on('error', reject);
+          ff.on('close', code => code === 0 ? resolve() : reject(new Error(`ffmpeg exit ${code}: ${ffErr.slice(-200)}`)));
+        });
+        fs.renameSync(tmpFile, filePath);
+
+        // Move to correct artist/album folder: {musicPath}/{safeArtistDir}/{albumName}/
+        const oldAlbumDir  = path.dirname(filePath);
+        const oldArtistDir = path.dirname(oldAlbumDir);
+        const albumName    = path.basename(oldAlbumDir);
+        const newAlbumDir  = path.join(CONFIG.musicPath, safeArtistDir, albumName);
+
+        if (newAlbumDir !== oldAlbumDir) {
+          fs.mkdirSync(newAlbumDir, { recursive: true });
+          const destFile = path.join(newAlbumDir, path.basename(filePath));
+          if (!fs.existsSync(destFile)) fs.renameSync(filePath, destFile);
+          // Clean up empty old dirs
+          try {
+            if (fs.readdirSync(oldAlbumDir).filter(f => !f.startsWith('.')).length === 0) {
+              fs.rmdirSync(oldAlbumDir);
+              if (fs.readdirSync(oldArtistDir).filter(f => !f.startsWith('.')).length === 0)
+                fs.rmdirSync(oldArtistDir);
+            }
+          } catch {}
+        }
+
+        done++;
+        updateJob(jobId, { progress: 10 + Math.round((done / songs.length) * 80), message: `${done}/${songs.length} Songs aktualisiert…` });
+        log(jobId, `✅ ${ndSong.title}`);
+      } catch (e) {
+        log(jobId, `❌ ${ndSong.title}: ${e.message}`);
+        errors++;
+      }
+    }
+
+    // Trigger Navidrome rescan
+    try {
+      const { s, t } = mkTok();
+      await fetch(`${ndUrl}/rest/startScan?u=${encodeURIComponent(user)}&t=${t}&s=${s}&v=1.16.1&c=novasonic&f=json`, { signal: AbortSignal.timeout(5000) });
+    } catch {}
+
+    const msg = errors > 0 ? `${done} aktualisiert, ${errors} Fehler` : `${done} Songs aktualisiert`;
+    updateJob(jobId, { status: 'done', progress: 100, message: msg });
+  })().catch(e => updateJob(jobId, { status: 'error', message: e.message }));
+});
+
 app.get('/api/status/:jobId', (req, res) => {
   const job = jobs.get(req.params.jobId);
   if (!job) return res.status(404).json({ error: 'Job not found' });
@@ -978,7 +1102,7 @@ app.post('/api/edit-metadata', async (req, res) => {
     const oldAlbumDir  = path.dirname(currentFile);
     const oldArtistDir = path.dirname(oldAlbumDir);
     const newAlbumName  = romajiAlbum       ? sanitize(romajiAlbum) : path.basename(oldAlbumDir);
-    const newArtistName = romajiAlbumArtist ? sanitize(romajiAlbumArtist.split(/[,;&]/)[0].trim()) : path.basename(oldArtistDir);
+    const newArtistName = (albumArtistSort || romajiAlbumArtist) ? sanitize((albumArtistSort || romajiAlbumArtist).split(/[,;&]/)[0].trim()) : path.basename(oldArtistDir);
     const newDir = path.join(CONFIG.musicPath, newArtistName, newAlbumName);
 
     if (newDir !== oldAlbumDir) {