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>

file_cache.py

@@ -1,4 +1,4 @@
-# file_cache.py
+# file_cache.py
 """
 Stub — the Anthropic Files API path has been removed.
 All context is now sent as inline chunked text via _send_anthropic_chunked.
@@ -16,7 +16,7 @@ class ASTParser:
     Currently supports Python.
     """
 
- def __init__(self, language: str):
+ def __init__(self, language: str) -> None:
   if language != "python":
    raise ValueError(f"Language '{language}' not supported yet.")
   self.language_name = language
@@ -141,7 +141,7 @@ class ASTParser:
    code_bytes[start:end] = bytes(replacement, "utf8")
   return code_bytes.decode("utf8")
 
-def reset_client():
+def reset_client() -> None:
  pass
 
 def content_block_type(path: Path) -> str:
@@ -150,7 +150,7 @@ def content_block_type(path: Path) -> str:
 def get_file_id(path: Path) -> Optional[str]:
  return None
 
-def evict(path: Path):
+def evict(path: Path) -> None:
  pass
 
 def list_cached() -> list[dict]: