Combines token-based authentication from upstream with proxy clustering:
- Session keys for JWT signing (SessionPrivateKey/SessionPublicKey)
- One-time token store for proxy authentication
- Cluster-targeted updates via SendReverseProxyUpdateToCluster
- ProxyCluster field derived from domain
- OIDC validation config support
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>