switchSpeakers method
Switch speakers (rotate between speakerphone and other outputs)
Implementation
Future<void> switchSpeakers() async {
// For mobile, we commonly toggle between speaker and earpiece/headset
_isSpeakerPhoneOn = !_isSpeakerPhoneOn;
await adapter.setSpeakerphoneOn(_isSpeakerPhoneOn);
// TODO: For Web/Desktop, iterate through audiooutput devices
}