refactor(types): auto -> None sweep across entire codebase

Applied 236 return type annotations to functions with no return values
across 100+ files (core modules, tests, scripts, simulations).
Added Phase 4 to python_style_refactor track for remaining 597 items
(untyped params, vars, and functions with return values).

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

tests/test_gui_diagnostics.py

@@ -12,7 +12,7 @@ spec.loader.exec_module(gui_legacy)
 from gui_legacy import App
 
 @pytest.fixture
-def app_instance():
+def app_instance() -> None:
  dpg.create_context()
  with patch('dearpygui.dearpygui.create_viewport'), \
  patch('dearpygui.dearpygui.setup_dearpygui'), \