refactor(tests): Add strict type hints to fourth batch of test files

tests/test_gui2_layout.py

@@ -1,9 +1,10 @@
+from typing import Generator
 import pytest
 from unittest.mock import patch
 from gui_2 import App
 
 @pytest.fixture
-def app_instance() -> None:
+def app_instance() -> Generator[App, None, None]:
  with (
   patch('gui_2.load_config', return_value={'gui': {'show_windows': {}}}),
   patch('gui_2.save_config'),
@@ -17,7 +18,7 @@ def app_instance() -> None:
  ):
   yield App()
 
-def test_gui2_hubs_exist_in_show_windows(app_instance):
+def test_gui2_hubs_exist_in_show_windows(app_instance: App) -> None:
  """
     Verifies that the new consolidated Hub windows are defined in the App's show_windows.
     This ensures they will be available in the 'Windows' menu.
@@ -33,7 +34,7 @@ def test_gui2_hubs_exist_in_show_windows(app_instance):
  for hub in expected_hubs:
   assert hub in app_instance.show_windows, f"Expected hub window '{hub}' not found in show_windows"
 
-def test_gui2_old_windows_removed_from_show_windows(app_instance):
+def test_gui2_old_windows_removed_from_show_windows(app_instance: App) -> None:
  """
     Verifies that the old fragmented windows are removed from show_windows.
     """