refactor(infra): cull unused infrastructure and file cache helpers

src/file_cache.py

@@ -704,15 +704,6 @@ class ASTParser:
 def reset_client() -> None:
  pass
 
-def content_block_type(path: Path) -> str:
- return "unsupported"
-
 def get_file_id(path: Path) -> Optional[str]:
  return None
 
-def evict(path: Path) -> None:
- pass
-
-def list_cached() -> List[Dict[str, Any]]:
- return []
-