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_gui2_mcp.py

@@ -5,7 +5,7 @@ import ai_client
 from events import EventEmitter
 
 @pytest.fixture
-def app_instance():
+def app_instance() -> None:
  if not hasattr(ai_client, 'events') or ai_client.events is None:
   ai_client.events = EventEmitter()
  with (