fix(test): Final synchronization and stability fixes for RAG stress test

- Improved AppController.ai_status to prevent overwriting 'sending...' with 'models loaded'.
- Enhanced 	est_rag_phase4_stress.py with robust polling and increased timeout.
- Synchronized App and AppController history objects to ensure consistent view.

tests/test_gui_window_controls.py

@@ -38,8 +38,9 @@ def test_gui_window_controls_minimize_maximize_close():
   # Let's say _render_custom_title_bar uses imgui.button
   # We will test the close button logic
   # Since it's UI code, we just simulate the conditions
-  mock_imgui.button.return_value = True # Simulate all buttons being clicked
-  
+  mock_imgui.button.return_value = True
+  mock_imgui.menu_item.return_value = (False, False)
+  # Simulate all buttons being clicked
   # Avoid hitting actual menu logic that requires real runner_params
   mock_imgui.begin_menu.return_value = False