feat(admin): AdminSidebar에 "설문 응답" 메뉴 추가

NAV_ITEMS 배열 끝에 /admin/survey 항목 (체크리스트 아이콘).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/admin/components/AdminSidebar.tsx

@@ -118,6 +118,16 @@ const NAV_ITEMS = [
       </svg>
     ),
   },
+  {
+    href: '/admin/survey',
+    label: '설문 응답',
+    icon: (
+      <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2}
+          d="M9 5H7a2 2 0 00-2 2v12a2 2 0 002 2h10a2 2 0 002-2V7a2 2 0 00-2-2h-2M9 5a2 2 0 002 2h2a2 2 0 002-2M9 5a2 2 0 012-2h2a2 2 0 012 2m-6 9l2 2 4-4" />
+      </svg>
+    ),
+  },
 ];
 
 interface AdminSidebarProps {