[copyberry]

Add local audio device selection to TUI voice settings

Why

Voice conversations previously opened the system-default microphone and speaker. Users need to choose which local devices to use, including when connected to a remote app server.

What changed

• Add input and output device pickers alongside voice selection, with back navigation and a System default option.
• Persist selections as audio.microphone and audio.speaker on the TUI's machine, excluding project configuration layers. Apply them to the next voice conversation.
• Enumerate devices without opening audio streams and pass the selected names to the voice helper at startup.
• Disable ambiguous device names in the picker and use the same eligibility filtering for discovery and named-device startup.

Testing

Add tests for device preference persistence across project and remote transitions, picker navigation and duplicate names, discovery without capture, and forwarding selected devices to the helper.

[github-actions]

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