Voice mode: show microphone mute state when Codex is not focused

What feature would you like to see?

Provide a clear, persistent way to tell whether the microphone is muted during a Codex voice session even when the Codex window is not focused.

Desired behavior

• The mute/unmute state remains visible outside the focused Codex UI, such as through a menu-bar, dock, system-level, or other persistent indicator.
• The state updates immediately when the microphone is toggled.
• The indicator makes it easy to avoid speaking into a muted session or accidentally leaving the microphone live while working in another app.

Why this matters

Voice sessions often continue while users switch applications. The current in-app state is not readily visible in that workflow.