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_user_agent.py

@@ -7,11 +7,11 @@ sys.path.append(os.path.abspath(os.path.join(os.path.dirname(__file__), "..")))
 
 from simulation.user_agent import UserSimAgent
 
-def test_user_agent_instantiation():
+def test_user_agent_instantiation() -> None:
  agent = UserSimAgent(hook_client=None)
  assert agent is not None
 
-def test_perform_action_with_delay():
+def test_perform_action_with_delay() -> None:
  agent = UserSimAgent(hook_client=None)
  called = False