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

tests/test_mma_agent_focus_phase1.py

@@ -9,22 +9,6 @@ import ai_client
 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()
-
-
 @pytest.fixture(autouse=True)
 def reset_tier():
  """Reset current_tier before and after each test."""