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

tests/test_gui2_mcp.py

@@ -1,11 +1,12 @@
 import pytest
 from unittest.mock import patch, MagicMock
+from typing import Generator
 from gui_2 import App
 import ai_client
 from events import EventEmitter
 
 @pytest.fixture
-def app_instance() -> None:
+def app_instance() -> Generator[App, None, None]:
  if not hasattr(ai_client, 'events') or ai_client.events is None:
   ai_client.events = EventEmitter()
  with (
@@ -21,7 +22,7 @@ def app_instance() -> None:
  ):
   yield App()
 
-def test_mcp_tool_call_is_dispatched(app_instance):
+def test_mcp_tool_call_is_dispatched(app_instance: App) -> None:
  """
     This test verifies that when the AI returns a tool call for an MCP function,
     the ai_client correctly dispatches it to mcp_client.