1. play_track now returns PlayTrackResult with format_id from Qobuz API
- Returns actual format (5=MP3, 6=FLAC16, 7=FLAC24, 27=Hi-Res)
- Returns None for cache hits (format unknown)
2. Frontend updates track.format based on format_id
- QualityBadge can now correctly show "MP3" when format_id=5
- Previously badge showed "CD" even for MP3 because format was empty
3. Device name now set after backend system init
- PipeWire and ALSA backends now set current_device from settings
- Fixes tooltip showing no device when using backend system