Mic Mute Toggle

Add a simple toggle to the OMI app that allows users to mute the microphone and temporarily stop listening/transcribing. Tapping the icon once mutes the mic; tapping it again unmutes.

Requirements
1. Toggle Button: Place a mute/unmute button at the top of the app UI for quick access.
2. On-Demand Control: A single tap mutes or unmutes immediately.
3. Phase-Two Enhancement (Optional): Provide a mute duration option (e.g., 60 minutes) that automatically unmutes the mic when the time is up.

Goal
Enable users to easily pause transcription for privacy or other reasons, then resume at any time.