Fix general settings route and req.user references

- Update frontend settings service to use correct /api/admin/settings/general route
- Fix all req.user to req.admin references in adminSettings.js
- Ensures settings can be saved without authentication errors

frontend/src/components/admin/index.ts

@@ -2,4 +2,6 @@ export { AdminLayout } from './AdminLayout';
 export { AdminSidebar } from './AdminSidebar';
 export { AdminHeader } from './AdminHeader';
 export { ThemeCustomizer } from './ThemeCustomizer';
-export { PasswordChangeModal } from './PasswordChangeModal';
+export { PasswordChangeModal } from './PasswordChangeModal';
+export { AdminAuthWrapper } from './AdminAuthWrapper';
+export { PhotoUpload } from './PhotoUpload';