fixed variable name

app.py

@@ -43,7 +43,7 @@ class BasicAgent:
         )
         print("BasicAgent initialized.")
     def __call__(self, question: str) -> str:
-        limiter.sleep_if_needed()
+        rate_limiter.sleep_if_needed()
         print(f"Agent received question (first 50 chars): {question[:50]}...")
         answer = self.agent.run(question)
         print(f"Agent returning answer: {answer}")