chore(tech-debt): Finalize gui_2.py cleanup and test suite discipline

tests/test_mma_agent_focus_phase3.py

@@ -7,22 +7,6 @@ from unittest.mock import patch
 from gui_2 import App
 
 
-@pytest.fixture
-def app_instance() -> Generator[App, None, None]:
- with (
-  patch('gui_2.load_config', return_value={'gui': {'show_windows': {}}}),
-  patch('gui_2.save_config'),
-  patch('gui_2.project_manager'),
-  patch('gui_2.session_logger'),
-  patch('gui_2.immapp.run'),
-  patch.object(App, '_load_active_project'),
-  patch.object(App, '_fetch_models'),
-  patch.object(App, '_load_fonts'),
-  patch.object(App, '_post_init')
- ):
-  yield App()
-
-
 def test_ui_focus_agent_state_var_exists(app_instance):
  """App.__init__ must expose ui_focus_agent: str | None = None."""
  assert hasattr(app_instance, 'ui_focus_agent'), "ui_focus_agent missing from App"