Implement Keycloak authentication integration and unify user management

.env.example

@@ -20,3 +20,15 @@ NUXT_DOCUMENSO_BASE_URL=https://signatures.portnimara.dev
 
 # Webhook Configuration for Embedded Signing
 WEBHOOK_SECRET_SIGNING=96BQQRiKkTIN2w0rHbqo7yHggV/sT8702HtHih3uNSY=
+
+# Keycloak Configuration
+KEYCLOAK_ISSUER=https://auth.portnimara.dev/realms/client-portal
+KEYCLOAK_CLIENT_ID=client-portal
+KEYCLOAK_CLIENT_SECRET=your-keycloak-client-secret
+KEYCLOAK_CALLBACK_URL=https://client.portnimara.dev/auth/callback
+# For local development, use: http://localhost:3000/auth/callback
+
+# OIDC Session Configuration
+OIDC_SESSION_SECRET=your-32-character-session-secret
+OIDC_ENCRYPT_KEY=your-32-character-encryption-key
+OIDC_ENCRYPT_IV=16-char-enc-iv!