## What changed
- Add a `GstAudioSink` subclass backed by a bounded mono `F32LE` playback writer, with partial writes, cancellation on speaker epoch changes, and delay accounting for queued samples and pending device output.
- Recreate the CPAL output stream and discard buffered audio when speaker controls change the epoch, preventing stale audio from surviving suppression.
- Add GStreamer dependencies, adjust Windows Bazel native-tool selection, and allow the helper handshake time to load startup-linked libraries.
- Separate installed-client tests from protocol lifecycle tests and supply native startup libraries in test packages.
## Testing
Add unit coverage for partial writes, sample accounting, suppression cancellation, stale writers, device delay, invalid samples, and stalled consumption.
GitOrigin-RevId: c48c48d2fee00659cf6f8a4039a6745385cb77cd
9daf7d22ca