refactor: remove redundant local imports already available at module level

Sweep ~74 redundant local imports across 21 files where the same module
was already imported at the top level. Also includes type fixes and lint
cleanups on the same branch.

tools/skills_tool.py

@@ -509,7 +509,6 @@ def _get_disabled_skill_names() -> Set[str]:
 
 def _is_skill_disabled(name: str, platform: str = None) -> bool:
     """Check if a skill is disabled in config."""
-    import os
     try:
         from hermes_cli.config import load_config
         config = load_config()