fix: improve Spotify importer metadata — copy iTunes durationMs, skip redundant backend lookup when frontend already enriched track

backend/novasonic-server.js

@@ -276,9 +276,18 @@ app.post('/api/download', async (req, res) => {
           const batchResults = await Promise.allSettled(batch.map(async track => {
             const trackTitle  = track.trackName  || '';
             const trackArtist = track.artistName || artist || '';
-            const searchArtist = trackArtist.split(',')[0].trim();
-            log(jobId, `📋 iTunes: "${trackArtist} – ${trackTitle}"`);
-            const itunes = await lookupItunesTrackMeta(searchArtist, trackTitle);
+            // If the frontend already enriched this track with iTunes data (collectionName +
+            // trackNumber + durationMs all present), skip the re-lookup to avoid a different
+            // iTunes result overriding the already-correct enriched metadata.
+            const alreadyEnriched = !!(track.collectionName && track.trackNumber && track.durationMs);
+            let itunes = {};
+            if (alreadyEnriched) {
+              log(jobId, `📋 Frontend-Metadaten: "${trackArtist} – ${trackTitle}" (${track.collectionName})`);
+            } else {
+              const searchArtist = trackArtist.split(',')[0].trim();
+              log(jobId, `📋 iTunes: "${trackArtist} – ${trackTitle}"`);
+              itunes = await lookupItunesTrackMeta(searchArtist, trackTitle);
+            }
             return downloadTrack({
               jobId,
               artist:      trackArtist,