Add selection_model field to autoselect configuration

- Add selection_model field to specify which rotation to use for model selection
- Default value is 'general' rotation
- Allows explicit control over which rotation models are available for autoselect
- Provides flexibility in configuring autoselect behavior

config/autoselect.json

@@ -2,6 +2,7 @@
   "autoselect": {
     "model_name": "autoselect",
     "description": "Auto-selects the best rotating model based on user prompt analysis",
+    "selection_model": "general",
     "fallback": "general",
     "available_models": [
       {