refactor: simplify OIDC provider configuration by using issuer-uri for auto-discovery

backend/src/main/resources/application.properties

@@ -8,12 +8,6 @@ spring.security.oauth2.client.registration.oidc.scope=openid,profile,email
 spring.security.oauth2.client.registration.oidc.authorization-grant-type=authorization_code
 spring.security.oauth2.client.registration.oidc.redirect-uri={baseUrl}/login/oauth2/code/{registrationId}
 
-# OIDC Provider endpoints - explicit to avoid HTTP call at startup.
-# OIDC_ISSUER_URI must be set to the issuer base URL (e.g. https://auth.example.com/oidc).
-# Spring will append the standard OIDC path segments below.
-# Adjust the paths below if your provider uses non-standard URLs.
-spring.security.oauth2.client.provider.oidc.authorization-uri=${OIDC_ISSUER_URI:http://localhost:8090/realms/voidAuth}/protocol/openid-connect/auth
-spring.security.oauth2.client.provider.oidc.token-uri=${OIDC_ISSUER_URI:http://localhost:8090/realms/voidAuth}/protocol/openid-connect/token
-spring.security.oauth2.client.provider.oidc.user-info-uri=${OIDC_ISSUER_URI:http://localhost:8090/realms/voidAuth}/protocol/openid-connect/userinfo
-spring.security.oauth2.client.provider.oidc.jwk-set-uri=${OIDC_ISSUER_URI:http://localhost:8090/realms/voidAuth}/protocol/openid-connect/certs
+# OIDC Provider - Spring auto-discovers all endpoints via .well-known/openid-configuration
+spring.security.oauth2.client.provider.oidc.issuer-uri=${OIDC_ISSUER_URI:http://localhost:8090/realms/voidAuth}
 spring.security.oauth2.client.provider.oidc.user-name-attribute=preferred_username