connect method
Connect to the media plane for a leg and start capturing/playing audio.
Implementation
@override
Future<void> connect(NexusJoinToken token) async {
NexusLog.warn('voice: no media engine registered — audio is inactive '
'(register one via Nexus.instance.voice.useEngine). Room=${token.room}');
_states.add(VoiceEngineState.connected);
_remote.add(1); // pretend a remote is present so control-plane flows proceed
}