fix: find renamed files by searching original Navidrome directory

When Navidrome has a stale index (e.g. file was renamed from
'01 - Idea 10.mp3' to '01 - Gibran Alcocer - Idea 10.mp3'),
_findFileInDir now falls back to the original file's directory
and matches by track-number prefix ('01 - ') so the renamed file
is found even without a Navidrome rescan.

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

backend/novasonic-server.js

@@ -697,9 +697,12 @@ app.get('/api/song-sorttags', async (req, res) => {
   } catch (e) { return res.status(502).json({ error: e.message }); }
   if (!path.isAbsolute(filePath)) filePath = path.join(CONFIG.musicPath, filePath);
   if (!fs.existsSync(filePath)) {
-    const rebased = _rebasePath(filePath, CONFIG.musicPath);
-    const found   = rebased || _findFileRecursive(CONFIG.musicPath, path.basename(filePath))
-                            || _findFileInDir(path.dirname(rebased || path.join(CONFIG.musicPath, path.basename(filePath))), path.basename(filePath));
+    const fileName   = path.basename(filePath);
+    const rebased    = _rebasePath(filePath, CONFIG.musicPath);
+    const rebasedDir = rebased ? path.dirname(rebased) : null;
+    const found      = rebased
+      || _findFileRecursive(CONFIG.musicPath, fileName)
+      || _findFileInDir(rebasedDir || path.dirname(filePath), fileName);
     if (found) filePath = found; else return res.status(404).json({ error: 'File not found' });
   }
   try {
@@ -765,14 +768,14 @@ app.post('/api/edit-metadata', async (req, res) => {
     const rebased    = _rebasePath(filePath, CONFIG.musicPath);
     const fileName   = path.basename(filePath);
     const rebasedDir = rebased ? path.dirname(rebased) : null;
+    // Also check the original dir — the file may have been renamed (e.g. artist added to filename)
+    // but Navidrome's index is stale and still points to the old name.
+    const originalDir = path.dirname(filePath);
     const found = rebased
       || _findFileRecursive(CONFIG.musicPath, fileName)
-      || (rebasedDir && _findFileInDir(rebasedDir, fileName));
+      || _findFileInDir(rebasedDir || originalDir, fileName);
     if (found) { filePath = found; }
-    else {
-      console.warn(`[edit-metadata] File not found. nd_path=${filePath} music_root=${CONFIG.musicPath} rebased=${rebased}`);
-      return res.status(404).json({ error: `File not found: ${filePath} (music root: ${CONFIG.musicPath})` });
-    }
+    else return res.status(404).json({ error: `File not found: ${filePath} (music root: ${CONFIG.musicPath})` });
   }
 
   // Resolve artwork: base64 > URL