resume method

@override Future<void> resume()

App 被杀后重新打开（resumable）：续期令牌、连接媒体。

Implementation

@override
Future<void> resume() async {
  if (!snapshot.resumable) throw invalidState('not_resumable');
  final renewed = await _module.signal('rtc.renew_token', '$_path/token', {'call_id': callId});
  final media = asMap(renewed['media']);
  if (media == null) throw invalidState('not_resumable');
  await attachMedia(media, asInt(renewed['heartbeat_interval_seconds']));
}