fix(auth): treat empty credential pool entries as unauthenticated

Fixes #28140

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

hermes_cli/model_switch.py

@@ -1232,7 +1232,7 @@ def list_authenticated_providers(
             try:
                 from hermes_cli.auth import _load_auth_store
                 store = _load_auth_store()
-                if store and hermes_id in store.get("credential_pool", {}):
+                if store and store.get("credential_pool", {}).get(hermes_id):
                     has_creds = True
             except Exception:
                 pass