- Added `STTMetadataFrame` to broadcast STT service latency information at pipeline start.
  - STT services broadcast P99 time-to-final-segment (`ttfs_p99_latency`) to downstream processors
  - Turn stop strategies automatically configure their STT timeout from this metadata
  - Developers can override `ttfs_p99_latency` via constructor argument for custom deployments
  - Added measured P99 values for STT providers.
  - See [stt-benchmark](https://github.com/pipecat-ai/stt-benchmark) to measure latency for your configuration