_buildAudioSource is now async and cache-aware:
1. Cache hit → AudioSource.uri(file://path)
2. Cache miss with manager → LockCachingAudioSource (cache-as-you-play)
3. No manager configured → plain AudioSource.uri (legacy fallback)
playerActionsProvider.playTracks now passes audioCacheManager into
configure() alongside coverCache. setQueueFromTracks awaits the source
build (Future.wait over the track list).
Out of scope: registering an index row when LockCachingAudioSource
finishes downloading (no clean hook from just_audio). Prefetcher /
Download buttons cover the index path.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
bvandeusen
153e931490