fix: delete cover.jpg and leftover webm/m4a after ffmpeg embed

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

backend/novasonic-server.js

@@ -458,6 +458,12 @@ async function downloadTrack({ jobId, artist, albumArtist, title, album, year, t
     ff.on('close', code => {
       if (code === 0 && fs.existsSync(tmpFile)) {
         fs.renameSync(tmpFile, audioFile);
+        if (hasCover) try { fs.unlinkSync(coverPath); } catch {}
+        // clean up any leftover webm the yt-dlp conversion didn't remove
+        const base = path.basename(audioFile, path.extname(audioFile));
+        for (const ext of ['webm', 'webm.part', 'm4a', 'opus']) {
+          try { fs.unlinkSync(path.join(dir, `${base}.${ext}`)); } catch {}
+        }
         log(jobId, `✅ Fertig${hasCover ? ' (Cover 1000x1000 eingebettet)' : ''}`);
       } else {
         try { fs.unlinkSync(tmpFile); } catch {}