Increase Spotify client rate limit and reduce API contention during watchlist scans. Changes:
- core/spotify_client.py: Bumped MIN_API_INTERVAL from 0.2s to 0.35s (~171 calls/min) to stay safely under Spotify's ~180/min limit.
- web_server.py: In start_watchlist_scan and automatic scan flow, pause spotify_enrichment_worker and itunes_enrichment_worker before scanning (tracking with _enrichment_was_running/_itunes_enrichment_was_running) and resume them in finally blocks; added console prints for pause/resume. This prevents enrichment workers from contending for API quota during long scans.
- webui/static/script.js: Improved enrichment status tooltip logic to prioritize explicit currentType and then fall back to completion-based inference with explicit branches for artists, albums, and tracks for clearer progress text.
These changes aim to avoid API rate violations and make scan progress display more predictable.