Speaker (output) mute existed in the legacy _AudioControls widget
and the rust.setOutputMuted bridge call but was lost when SDD-097
replaced _AudioControls with VoiceBar. Mic mute carried over;
speaker mute did not.
Wire it back: VoiceBar gains an outputMuted prop + onToggleOutputMute
callback and renders a headset/headset_off icon next to the
existing mic mute. main.dart wires the existing _toggleOutputMute
handler (previously dead-code with // ignore: unused_element). The
bridge call setOutputMuted already does both effects together:
local engine silencer + server-broadcast ClientOutputMuted flag.
l10n: rename voiceHardMuteLabel to 'Mute microphone'/'麦克风静音'
to distinguish from the new voiceOutputMuteLabel 'Mute speakers'/
'扬声器静音'.
flutter analyze: clean (6 pre-existing Radio.groupValue infos).