Added comprehensive logging to FlacCacheSink::process():
- Process start
- Waiting for/receiving first audio chunk
- FLAC encoder creation
- Cache ingestion and pump parallel execution
- tokio::join! completion
- Track added to cache confirmation
Testing results show PROGRESSIVE CACHING WORKS:
✅ Prebuffer reached in 0.6 seconds
✅ Track added to cache with pk
✅ Download pipeline completes successfully
✅ Playlist receives track
✅ Playback starts
Current timing:
- t=0.6s: Prebuffer complete (512KB)
- t=3.6s: Track added to playlist (after pump completes)
- t=4.5s: Playback starts
The 3s delay is because tokio::join! waits for BOTH futures:
- cache_future (returns after prebuffer ~0.6s)
- pump_future (pumps entire first track ~3s)
For true 1-2s startup, would need to refactor to push to playlist
immediately after prebuffer, without waiting for pump to complete.
ed0bbfbf69