## Why
Voice mute used a hard-coded `Ctrl+X` shortcut and footer hint, so keymap customization could not change or disable it.
## What changed
- Wire `tui.keymap.chat.toggle_voice_mute` into runtime keybindings and the keymap picker, supporting custom keys, chords, and unbinding.
- Keep `Ctrl+X` as the default, but let existing configured shortcuts and overlapping chord prefixes take precedence. Validate explicitly configured mute bindings for conflicts.
- Activate voice chords only when the microphone shortcut is available, excluding pagers and overlays.
- Refresh the voice footer when bindings change, showing the configured shortcut or `/voice mute` when unbound.
## Testing
Add regression tests for binding resolution, conflicts, voice chord context, and live keymap updates. Add footer snapshots covering custom keys, chords, and unbinding in muted and listening states at wide and narrow widths.
GitOrigin-RevId: ec9385f3956aa268bba34dcf2cc2b0c92a31bfec
Benjamin Carlsson
45305dd229