…uthorization Code authentication flow.

…k method

…n controller

…w handles all token verification, and error redirects are securely validated against the KEYCLOAK_URL to prevent open redirect vulnerabilities

…handling

…lm, clientId, clientSecret) are now initialized once in the class constructor as private readonly properties

…oded logic

…LBACK_BASE_PATH'

… PKCE logic, and refactor frontend OIDC integration.

…ng Keycloak integration, environment setup, backend implementation, frontend integration, and troubleshooting steps.

…p" from package-lock.json and package.json

…API, Frontend, Keycloak, and OIDC integration

…ent setup

…OIDC identity handling