Add JWT-based security and /me endpoint

Introduced JWT-based authentication with role handling using Keycloak. Added the `/me` endpoint to return user information and roles. Configured testing, Keycloak integration, and public-facing `/public/info` endpoint enhancements.

src/main/resources/application.yml

@@ -11,3 +11,8 @@ spring:
       ddl-auto: none
   flyway:
     enabled: true
+  security:
+    oauth2:
+      resourceserver:
+        jwt:
+          issuer-uri: http://localhost:8082/realms/hemhub