fix(app_controller): fix cost_tracker import in get_session_insights

src/app_controller.py

@@ -1765,7 +1765,7 @@ class AppController:
   self._update_cached_stats()
 
  def get_session_insights(self) -> Dict[str, Any]:
-  import cost_tracker
+  from src import cost_tracker
   total_input = sum(e["input"] for e in self._token_history)
   total_output = sum(e["output"] for e in self._token_history)
   total_tokens = total_input + total_output