fix: pass model_type as positional arg to camel-ai ModelFactory.create

model_type must be a separate argument, not inside model_config_dict.
Also ensure all 3 scripts have consistent ModelFactory.create calls.

backend/scripts/run_twitter_simulation.py

@@ -463,6 +463,7 @@ class TwitterSimulationRunner:
         
         return ModelFactory.create(
             model_platform=ModelPlatformType.OPENAI,
+            model_type=llm_model,
             model_config_dict=model_config,
         )