Resolve Spotify artist matching through the exact Spotify client only, so watchlist ID backfill cannot drift to fallback-provider results. Remove the remaining preemptive provider availability check from the backfill loop.
Move the web watchlist scan core onto the shared metadata source priority so primary provider settings are respected during artist, album, and image resolution.
Add coverage for primary-source-first discography lookup and fallback to later providers when the primary source has no albums.
Bring placeholder tracklist skipping back into the shared watchlist scan path, and centralize the DB-only artist image backfill helper so both web scan entrypoints reuse the same logic.
Move the shared watchlist scan loop into core/watchlist_scanner.py so web_server.py only handles triggers, locks, progress, and post-scan orchestration.
Manual and scheduled watchlist scans now share the same scanner-side core, while the web entrypoints keep profile selection and automation progress updates.
