Fix set_default_model_type function bug

- Corrected function to set 'default_model_type' instead of 'default_model'
- Fixed NameError where 'model' variable was undefined
- Now properly saves model type configuration

vidai/config.py

@@ -109,8 +109,8 @@ def get_default_model_type() -> str:
 
 
 def set_default_model_type(model_type: str) -> None:
-    """Set the default model path."""
-    set_config('default_model', model)
+    """Set the default model type."""
+    set_config('default_model_type', model_type)
 
 
 def get_frame_interval() -> int: