User can select microphone source and receive improved transcription accuracy on the glasses

[saraayy]

Tasks

• Implement support for both glasses microphone and phone microphone.
• Add microphone source selection logic in the frontend.
• Add UI option for selecting microphone source.
• Ensure the selected microphone remains active during the entire recording session.
• Ensure audio stream format is compatible with backend processing.
• Verify that transcription works with both microphone sources.
• Ensure existing recording start/stop logic is not broken.

Definition of Done

• User can select either glasses microphone or phone microphone before recording.
• The selected microphone is actually used during recording.
• Audio stream is successfully sent to the backend from both sources.
• Transcription is successfully generated using both microphone sources.
• No regression in existing recording start/stop functionality.
• End-to-end flow works (speech → backend → glasses).
• Code reviewed and approved.