Implemented Gradio testing UI with STT/TTS tabs. **Changes made:** - Created `src/librechat_audio/gradio_app.py` with: - STT tab: Record audio via microphone or upload file, select Local (parakeet-mlx) or OpenAI (Whisper) backend - TTS tab: Enter text, select Local (Chatterbox) or OpenAI backend, voice selection for OpenAI - Status messages for feedback - Graceful handling when backends are unavailable - Updated `pyproject.toml`: - Added `[ui]` optional dependency group with gradio>=4.0.0 - Added `librechat-audio-ui` console script entry point - Updated `src/librechat_audio/__init__.py`: - Exported `create_gradio_app` function - Created `tests/test_gradio_app.py` with 20 tests covering: - Module imports and availability flags - Client helper functions - Transcription and synthesis functions - Error handling when backends unavailable - Package exports **Verification:** - All 423 tests pass (403 existing + 20 new) - Gradio app can be launched with `librechat-audio-ui` command **Usage:** ```bash pip install 'librechat-audio[ui]' # Install with Gradio librechat-audio-ui # Launch the UI ```