- Add minimax to PROVIDERS lists in gui_2.py and app_controller.py
- Add minimax credentials template in ai_client.py
- Implement _list_minimax_models, _classify_minimax_error, _ensure_minimax_client
- Implement _send_minimax with streaming and reasoning support
- Add minimax to send(), list_models(), reset_session(), get_history_bleed_stats()
- Add unit tests in tests/test_minimax_provider.py
