Cloudflare AI Gateway standardizes credential rejection responses to HTTP 401 with error code 2009

Cloudflare AI Gateway now standardizes credential rejection responses across all providers. According to the [Cloudflare changelog](https://developers.cloudflare.com/changelog/post/2026-10-05-provider-credential-errors/), all providers return an HTTP 401 status code with error code 2009 to provide consistent error handling.