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/config.py

@@ -2214,7 +2214,6 @@ def print_config_warnings(config: Optional[Dict[str, Any]] = None) -> None:
     if not issues:
         return
 
-    import sys
     lines = ["\033[33m⚠ Config issues detected in config.yaml:\033[0m"]
     for ci in issues:
         marker = "\033[31m✗\033[0m" if ci.severity == "error" else "\033[33m⚠\033[0m"
@@ -2229,7 +2228,6 @@ def warn_deprecated_cwd_env_vars(config: Optional[Dict[str, Any]] = None) -> Non
     These env vars are deprecated — the canonical setting is terminal.cwd
     in config.yaml.  Prints a migration hint to stderr.
     """
-    import os, sys
     messaging_cwd = os.environ.get("MESSAGING_CWD")
     terminal_cwd_env = os.environ.get("TERMINAL_CWD")
 
@@ -3238,7 +3236,6 @@ def _check_non_ascii_credential(key: str, value: str) -> str:
             bad_chars.append(f"  position {i}: {ch!r} (U+{ord(ch):04X})")
     sanitized = value.encode("ascii", errors="ignore").decode("ascii")
 
-    import sys
     print(
         f"\n  Warning: {key} contains non-ASCII characters that will break API requests.\n"
         f"  This usually happens when copy-pasting from a PDF, rich-text editor,\n"