Integrate Keycloak authentication

[sdley]

• Add the spring-boot-starter-security and spring-boot-starter-oauth2-resource-server dependencies to the project.​
• Deploy Keycloak (often in Docker) and configure a realm, client, and roles (admin, client, agent) as needed.​
• In the Spring Boot application, configure Keycloak integration in the application.properties file and update the code to map roles/authorities appropriately.​
• Assign users to roles in Keycloak and update the backend logic to enforce role-based access.