Transcribe audio

filename must be a local path that the SDK can read on the current device, not a URL, Base64 value, or uploaded file name:

final result = await OpenIM.iMManager.messageManager.speechToText(
  filename: soundElem.soundPath!,
);
final transcript = result.text ?? '';

If only a remote URL is available, download it to a controlled local path first. The Future returns SpeechToTextResp; it does not modify the original message or trigger a listener. Before calling it, check speech recognition support.