feat(provider): Add MiniMax AI provider integration

- 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

project_history.toml

@@ -8,5 +8,5 @@ active = "main"
 
 [discussions.main]
 git_commit = ""
-last_updated = "2026-03-06T16:40:04"
+last_updated = "2026-03-06T23:22:48"
 history = []