Nous Portal is OAuth-only (auth_type=oauth_device_code, no API key path),
but the non-retryable-401 guidance branch only covered openai-codex and
xai-oauth. A Nous 401 fell through to the generic 'Your API key was
rejected... run hermes setup' message, which is wrong advice — the user
needs hermes auth add nous --type oauth, not an API key.
Also flag the case where the failing model slug ends in :free (OpenRouter
syntax) while provider is nous. Without that hint, users re-OAuth
successfully and then hit the same 401 on the next message because Nous
Portal doesn't carry the OpenRouter free-tier slug.
Reported by ashh — debug dump showed Nous device_code exhausted +
deepseek/deepseek-v4-flash:free as the model.
