fix: add fallback for base model repo list and filter "None" api_key

- Add hardcoded fallback list for Base Model Auto Loader dropdown when
  cache is empty and ModelScope API query hasn't completed yet
- Filter "None"/"none" api_key values in shared workflows so auth
  falls back to local config.json instead of sending invalid credentials

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>