Backend:
- Added play_count and days_since_played to rule engine field whitelist
- days_since_played uses julianday() expression with COALESCE for NULL handling
- Never-played tracks (NULL last_played) match 'greater_than' but not 'less_than'
- Added PlayCount + LastPlayed to library.Track struct
- Evaluate query selects play_count and last_played from track_metadata
- Added play_count to sort field options
Frontend:
- Added play_count and days_since_played to field and numeric field lists
- Added play_count to sort options
All 49 rule engine + 15 service tests pass unchanged.
yonlu
9c85cfcc7b