Fix speech to text on macOS

[dgageot]

Fixes #1919

[dgageot]

/review

[docker-agent]

Review Summary

Assessment: 🟢 APPROVE

This PR correctly implements speech-to-text functionality for macOS with proper channel lifecycle management and goroutine coordination. The code was thoroughly analyzed for concurrency issues, resource leaks, and error handling. All potential concerns were verified and found to be false positives:

✅ Channel safety: The transcriber callback captures its channel reference at creation time, preventing race conditions when the channel is closed
✅ Goroutine lifecycle: closeTranscriptCh() properly unblocks waiting goroutines; the IsRunning() guard prevents overlapping sessions
✅ Message ordering: Bubble Tea's event loop ensures all buffered transcript deltas are processed before sending content
✅ Error handling: The error path correctly returns early without setting recording UI state

The implementation demonstrates good understanding of Go concurrency patterns and Bubble Tea's event-driven architecture.

Code Quality Notes

• The buffered channel (capacity 100) with select-default pattern appropriately prevents blocking the audio thread
• Cleanup in cleanupAll() properly stops the transcriber and closes channels
• The Enter/ESC key handling during transcription is intuitive and well-implemented

Recommendation: Ready to merge ✅

[aheritier]

LGTM