- Add get_artist_top_tracks to Last.fm client (up to 100 tracks)
- Include lastfm_listeners, lastfm_playcount, lastfm_tags, lastfm_bio,
and soul_id in artist detail API response
- New endpoint: /api/artist/<id>/lastfm-top-tracks for lazy loading
- Hero layout: image (160px) | center (name, badges, genres, bio,
listener/play stats, progress bars) | right card (scrollable top
100 tracks from Last.fm)
- Badges 36px with hover lift, bio in subtle card with Read More
toggle, Last.fm tags merged with existing genres
- Numbers formatted: 1234567 → 1.2M
- Graceful degradation: sections hidden when Last.fm data unavailable
