feat: add design request management page

- Introduced a new Design Request page for managing design requests, including functionalities for creating, updating, and deleting requests.
- Implemented client-side filtering and progress tracking for design requests, enhancing user experience and data management.
- Integrated a combobox for selecting customers and orders, improving the efficiency of data entry.
- Added necessary types and styles for better organization and visual representation of design request statuses.

These changes aim to provide a comprehensive interface for managing design requests, facilitating better tracking and organization within the application.

frontend/components/layout/AdminPageRenderer.tsx

@@ -93,6 +93,7 @@ const ADMIN_PAGE_REGISTRY: Record<string, React.ComponentType<any>> = {
   // 설계 관리 (커스텀 페이지)
   "/design/task-management": dynamic(() => import("@/app/(main)/design/task-management/page"), { ssr: false, loading: LoadingFallback }),
   "/design/my-work": dynamic(() => import("@/app/(main)/design/my-work/page"), { ssr: false, loading: LoadingFallback }),
+  "/design/design-request": dynamic(() => import("@/app/(main)/design/design-request/page"), { ssr: false, loading: LoadingFallback }),
 
   // 영업 관리 (커스텀 페이지)
   "/sales/shipping-plan": dynamic(() => import("@/app/(main)/sales/shipping-plan/page"), { ssr: false, loading: LoadingFallback }),