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.

hermes_cli/web_server.py

@@ -2324,12 +2324,10 @@ def start_server(
         )
 
     if open_browser:
-        import threading
         import webbrowser
 
         def _open():
-            import time as _t
-            _t.sleep(1.0)
+            time.sleep(1.0)
             webbrowser.open(f"http://{host}:{port}")
 
         threading.Thread(target=_open, daemon=True).start()