Watchlist scanner: empty discography (no new releases in lookback) was
treated as API failure, causing "Failed to get artist discography" for
artists like Kendrick Lamar who simply had no recent releases. Now
distinguishes None (API failure → try next source) from [] (success,
no new tracks). Spotify backfill now uses the authenticated client
instance instead of creating a fresh unauthenticated one.
Wishlist nebula: album remove now sends album_name (API updated to
accept album_name as fallback alongside album_id). Track remove
re-renders the nebula after deletion. Toned down processing pulse
animation.
Updated test to verify fallback triggers on API failure (None), not
on empty results.