feat(admin): 주문 관리 페이지 — 입금 확인 원클릭 + 다운로드 활성화 메일

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/admin/components/AdminSidebar.tsx

@@ -36,6 +36,16 @@ const NAV_ITEMS = [
       </svg>
     ),
   },
+  {
+    href: '/admin/orders',
+    label: '주문 관리',
+    icon: (
+      <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2}
+          d="M3 3h2l.4 2M7 13h10l4-8H5.4M7 13L5.4 5M7 13l-2.293 2.293c-.63.63-.184 1.707.707 1.707H17m0 0a2 2 0 100 4 2 2 0 000-4zm-8 2a2 2 0 11-4 0 2 2 0 014 0z" />
+      </svg>
+    ),
+  },
   {
     href: '/admin/contacts',
     label: '문의 내역',