auth_test.go (6): T:153 GetAuthErrClosedState written as pure unit test;
T:147/149-152 use RunServer/RunServerWithConfig → deferred.
auth_callout_test.go (31): all use NewAuthTest (RunServer) → all deferred.
config_check_test.go (3): depend on Go .conf-format parser not yet ported → deferred.
Adds 7 new test methods to AuthHandlerTests; suite grows 638→645.
Implement ConfigureAuthorization, CheckAuthentication, and full auth
dispatch in NatsServer.Auth.cs; add HandleSignals in NatsServer.Signals.cs;
extend AuthHandler with GetAuthErrClosedState, ValidateProxies,
GetTlsAuthDcs, CheckClientTlsCertSubject, ProcessUserPermissionsTemplate;
add ReadOperatorJwt/ValidateTrustedOperators to JwtProcessor; add
AuthCallout stub; add auth accessor helpers to ClientConnection; add
NATS.NKeys package for NKey signature verification; 12 new tests pass.
