fetch_api_models is imported locally inside _model_flow_named_custom from
hermes_cli.models, not defined as a module-level attribute of hermes_cli.main.
Patch the source module so the local import picks up the mock.
Also force simple_term_menu ImportError so tests reliably use the input()
fallback path regardless of environment.
Co-Authored-By: Claude <noreply@anthropic.com>