Add settings endpoints and registration status check: implement new API endpoints for settings management, including registration status retrieval, and update the registration command handler to enforce registration rules based on site settings.

frontend/src/routes/admin.tsx

@@ -57,6 +57,13 @@ function AdminLayout() {
         >
           {t('admin.maintenance.title')}
         </Link>
+        <Link
+          to="/admin/settings"
+          className={cn('pb-2 uppercase tracking-wide text-muted-foreground hover:text-foreground')}
+          activeProps={{ className: 'border-b-2 border-primary text-primary' }}
+        >
+          {t('admin.settings.title')}
+        </Link>
       </nav>
       <Outlet />
     </div>