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_gemini_cli_parity_regression.py

@@ -9,7 +9,7 @@ sys.path.append(os.path.abspath(os.path.join(os.path.dirname(__file__), "..")))
 import ai_client
 
 @pytest.fixture(autouse=True)
-def setup_ai_client():
+def setup_ai_client() -> None:
  ai_client.reset_session()
  ai_client.set_provider("gemini_cli", "gemini-2.5-flash")
  ai_client.confirm_and_run_callback = lambda script, base_dir: "Mocked execution"