Add Keycloak integration support

- Update domain configuration to portal subdomain with HTTPS
- Add keycloak_id field to member creation and update operations
- Add API endpoint for linking Keycloak accounts to existing members

.env.example

@@ -35,5 +35,5 @@ NUXT_SESSION_SECRET=your-48-character-session-secret-key-here
 NUXT_ENCRYPTION_KEY=your-32-character-encryption-key-here
 
 # Public Configuration
-NUXT_PUBLIC_DOMAIN=monacousa.org
+NUXT_PUBLIC_DOMAIN=https://portal.monacousa.org
 #