Fix pyright: annotate FakeIPython.config type

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: BabyChrist666

tests/client/test_stdio.py

@@ -705,7 +705,7 @@ def test_jupyter_detection_ipkernel_app(self):
         """Test that _is_jupyter_environment returns True for IPKernelApp config."""
 
         class FakeIPython:
-            config = {"IPKernelApp": {}}
+            config: dict[str, dict[str, str]] = {"IPKernelApp": {}}
 
         mock_ipython_module = MagicMock()
         mock_ipython_module.get_ipython = MagicMock(return_value=FakeIPython())