Implement a new pmoaudio source node that streams Radio Paradise blocks
with automatic TrackBoundary insertion at the correct timing.
Features:
- Downloads and decodes FLAC blocks from Radio Paradise API
- Queue management for block IDs via push_block_id()
- Recent blocks cache (10 blocks) to avoid re-downloads
- Automatic TrackBoundary insertion based on sample count timing
- Converts Song metadata to TrackMetadata with cover URLs
- Timeout of 3 seconds for new block IDs (radio real-time)
- Support for 16-bit and 24-bit FLAC audio
Architecture:
- RadioParadiseStreamSourceLogic: Pure business logic implementing NodeLogic
- RadioParadiseStreamSource: Wrapper using Node<> pattern
- Uses logic_mut() for push_block_id() configuration
The node emits:
- TopZeroSync at block start
- TrackBoundary before each song (with same order as next chunk)
- Audio chunks (I16 or I24)
- EndOfStream on timeout or completion
New pmoaudio feature gate with dependencies on:
- pmoaudio, pmoflac, pmometadata, futures-util
