Update alphaear skills to use MiniMax as default LLM

Changes:
- Added 'minimax' provider to LLM factory
- Changed default LLM_PROVIDER from 'ust' to 'minimax'
- Changed default LLM_MODEL from 'Qwen' to 'MiniMax-Text-01'
- Updated REASONING_MODEL_PROVIDER and TOOL_MODEL_PROVIDER to minimax
- Sentiment tools now prefer MINIMAX_API_KEY over UST_KEY_API
- .env.example updated with MiniMax defaults

skills/alphaear-predictor/scripts/utils/predictor/training.py

@@ -97,7 +97,7 @@ class AutoSynthesisTrainer:
         self.model.load_state_dict(base_model.state_dict(), strict=False)
 
         # LLM for causality verification
-        provider = os.getenv("LLM_PROVIDER", "ust")
+        provider = os.getenv("LLM_PROVIDER", "minimax")
         model_id = os.getenv("LLM_MODEL", "Qwen")
         self.llm_agent = Agent(model=get_model(provider, model_id))