remove: lyrics downloading (fetchLyrics, .lrc files, uslt tag embedding)

Removes LRCLIB lookup, .lrc sidecar file writing, and lyrics/uslt
metadata embedding from all downloads.

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

backend/lib/ytdlp.js

@@ -5,7 +5,7 @@ const CONFIG    = require('./config');
 const { log }   = require('./jobs');
 const {
   sanitize, navidromeArtist,
-  downloadArtwork, fetchLyrics, findExistingTrack,
+  downloadArtwork, findExistingTrack,
 } = require('./metadata');
 
 function buildTitleKeywords(title) {
@@ -283,20 +283,9 @@ async function downloadTrack({ jobId, artist, albumArtist, title, album, year, t
 
 // Shared ffmpeg metadata embedding — used by both yt-dlp and squid paths
 async function embedMetadata({ jobId, audioFile, dir, trackPrefix, safeTitle, artist, mainArtist, album, year, trackNum, totalTracks, discNum, discTotal, compilation, genre, artworkUrl, explicit, title }) {
-  const [coverPath, lyricsData] = await Promise.all([
-    downloadArtwork(artworkUrl, dir),
-    fetchLyrics(artist, title, album),
-  ]);
+  const coverPath = await downloadArtwork(artworkUrl, dir);
   const hasCover = !!(coverPath && fs.existsSync(coverPath));
 
-  if (lyricsData?.synced) {
-    const lrcPath = path.join(dir, `${trackPrefix}${safeTitle}.lrc`);
-    fs.writeFileSync(lrcPath, lyricsData.synced, 'utf8');
-    log(jobId, '🎵 Synced lyrics gefunden');
-  } else if (lyricsData?.plain) {
-    log(jobId, '📝 Lyrics gefunden');
-  }
-
   log(jobId, `🏷  Metadaten + Cover → ${path.basename(audioFile)}`);
 
   const fileExt = path.extname(audioFile);
@@ -322,7 +311,6 @@ async function embedMetadata({ jobId, audioFile, dir, trackPrefix, safeTitle, ar
     if (discNum)     ffArgs.push('-metadata', `disc=${discTotal ? `${discNum}/${discTotal}` : String(discNum)}`);
     if (compilation) ffArgs.push('-metadata', `compilation=1`);
     if (explicit)    ffArgs.push('-metadata', 'ITUNESADVISORY=1');
-    if (lyricsData?.plain) ffArgs.push('-metadata', `lyrics=${lyricsData.plain}`);
     if (hasCover) {
       ffArgs.push(
         '-metadata:s:v', 'title=Album cover',