The metadata-only optimization broke two things:
1. Cards showed 0 tracks because tracks were no longer in the listing
2. Auto-mirror skipped all playlists because tracks array was empty
Fix: cards render instantly from metadata, then tracks are fetched
per-playlist in the background via /api/tidal/playlist/<id>. As each
playlist's tracks arrive, the card count updates and the playlist
is auto-mirrored. Also tried multiple V2 attribute names for track
count (numberOfTracks, numberOfItems, etc.) and fixed the card DOM
selector for count updates.