Add speech-to-text functionality for voice messages using OpenAI/Groq Whisper API. Includes:
- Configurable speech provider (OpenAI or Groq)
- Audio format conversion via ffmpeg
- Support for voice messages on Feishu, WeChat Work, Telegram, LINE, Discord, Slack
- Internationalization messages for voice transcription flow
- Documentation updates in README and config example
generated by llmgit
Co-Authored-By: Claude <noreply@anthropic.com>