## Why
ChatGPT token refresh requests need to follow the same configured routing policy as other authentication traffic, including environments that use the system proxy.
## What changed
- Require an `AuthRouteConfig` throughout login, logout, token refresh, personal access token, and agent identity flows.
- Build auth HTTP clients directly from that configuration instead of falling back to a default HTTP client when routing configuration is absent.
## Testing
- Add an integration test that refreshes a token through a cached system-proxy route and verifies the proxy receives the expected request.
GitOrigin-RevId: 7d54ab3219939a49921c51faf08cd4c2eabca51c