Implement OIDC for User Authentication

[TemaDeveloper]

This task is to implement support for OpenID Connect (OIDC) in the Spring Boot backend. This will allow the server to protect endpoints and validate a user's identity based on an ID Token issued by an authorization server.

Tasks:

• Add and configure Spring Security for OIDC and JWT support.
• Set up the backend as an OIDC resource server to validate incoming ID Tokens.
• Configure token validation to check the signature, issuer, and claims.
• Create a mechanism to map the validated claims from the ID Token to a user's security principal, establishing an authenticated session.