CVE-2026-49254: Dragonfly Manager OAuth provider client_secret disclosure via unauthenticated GET /api/v1/oauth

The Dragonfly Manager exposes GET /api/v1/oauth and GET /api/v1/oauth/:id to unauthenticated clients. The response body deserializes the entire manager/models.Oauth struct, which includes the client_secret field. Any network-reachable attacker can read the OAuth client secrets configured for github or google providers, defeating the confidentiality guarantee of those secrets and enabling subsequent abuse against the connected identity providers.