Implement native CAS protocol ticket validation for enterprise SSO
integration, supporting both CAS 2.0 (XML) and CAS 3.0 (JSON) modes.
Backend:
- Introduce IdentityClaims interface to abstract identity providers;
OAuthClaims now implements it, enabling CAS reuse of IdentityBindingService
- CasProperties with @PostConstruct HTTPS validation and feature flag
- CasTicketValidator: validates tickets via /serviceValidate (2.0) or
/p3/serviceValidate (3.0), parses XML/JSON responses
- CasLoginController: /api/v1/auth/cas/login (redirect) and /callback
(ticket validation + session establishment)
- RouteSecurityPolicyRegistry: permit /api/v1/auth/cas/**
- AuthMethodCatalog: expose CAS as CAS_REDIRECT method type
Frontend:
- LoginButton renders CAS_REDIRECT methods alongside OAuth providers
- Runtime config adds authCasEnabled flag
- CAS logo SVG added
Closes#456
