test: Update tests to mock async_dispatch for asynchronous tool execution engine.

tests/test_gui2_mcp.py

@@ -1,3 +1,4 @@
+import unittest.mock
 from unittest.mock import patch, MagicMock
 from src.gui_2 import App
 from src import ai_client
@@ -35,7 +36,7 @@ def test_mcp_tool_call_is_dispatched(app_instance: App) -> None:
  # 4. Patch the necessary components
  with patch("src.ai_client._ensure_gemini_client"), \
    patch("src.ai_client._gemini_client") as mock_client, \
-   patch("src.mcp_client.dispatch", return_value="file content") as mock_dispatch:
+   patch("src.mcp_client.async_dispatch", new_callable=unittest.mock.AsyncMock, return_value="file content") as mock_dispatch:
   mock_chat = mock_client.chats.create.return_value
   mock_chat.send_message.side_effect = [mock_response_with_tool, mock_response_final]
   ai_client.set_provider("gemini", "mock-model")