fix "unknown model type" error when rebasing a model with API

- Add command-line model probing script for dev use
- Minor documentation tweak

invokeai/backend/model_management/model_manager.py

@@ -391,6 +391,10 @@ class ModelManager(object):
         base_model: BaseModelType,
         model_type: ModelType,
     ) -> str:
+        # In 3.11, the behavior of (str,enum) when interpolated into a
+        # string has changed. The next two lines are defensive.
+        base_model = BaseModelType(base_model)
+        model_type = ModelType(model_type)
         return f"{base_model.value}/{model_type.value}/{model_name}"
 
     @classmethod