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_deepseek_infra.py

@@ -24,7 +24,7 @@ def test_credentials_error_mentions_deepseek(monkeypatch):
  assert "[deepseek]" in err_msg
  assert "api_key" in err_msg
 
-def test_default_project_includes_reasoning_role():
+def test_default_project_includes_reasoning_role() -> None:
  """
     Verify that 'Reasoning' is included in the default discussion roles
     to support DeepSeek-R1 reasoning traces.
@@ -33,14 +33,14 @@ def test_default_project_includes_reasoning_role():
  roles = proj["discussion"]["roles"]
  assert "Reasoning" in roles
 
-def test_gui_providers_list():
+def test_gui_providers_list() -> None:
  """
     Check if 'deepseek' is in the GUI's provider list.
     """
  import gui_2
  assert "deepseek" in gui_2.PROVIDERS
 
-def test_deepseek_model_listing():
+def test_deepseek_model_listing() -> None:
  """
     Verify that list_models for deepseek returns expected models.
     """