Update LangGraphAgent to use ChatOpenRouter model instead of ChatGoogleGenerativeAI

agent.py

@@ -74,8 +74,12 @@ class LangGraphAgent:
 
         # Choose an LLM if not provided
         if model is None:
-            model = ChatGoogleGenerativeAI(
-                model="gemma-3-27b-it",
+            # model = ChatGoogleGenerativeAI(
+            #     model="gemma-3-27b-it",
+            # )
+            model = ChatOpenRouter(
+                model="openai/gpt-oss-20b:free",
+                temperature=0.1,
             )
             if model is None and ChatOpenAI is not None:
                 model = ChatOpenAI(