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/models.py

@@ -515,8 +515,6 @@ def check_nous_free_tier() -> bool:
     Returns False (assume paid) on any error — never blocks paying users.
     """
     global _free_tier_cache
-    import time
-
     now = time.monotonic()
     if _free_tier_cache is not None:
         cached_result, cached_at = _free_tier_cache
@@ -1259,7 +1257,6 @@ def detect_provider_for_model(
             from hermes_cli.auth import PROVIDER_REGISTRY
             pconfig = PROVIDER_REGISTRY.get(direct_match)
             if pconfig:
-                import os
                 for env_var in pconfig.api_key_env_vars:
                     if os.getenv(env_var, "").strip():
                         has_creds = True