feat: 관리자 수동 이미지 대체 기능 추가

frontend/src/lib/api.js

@@ -104,6 +104,8 @@ export const api = {
   cleanupAdminUnusedImageAssets: (payload) => request('/api/admin/image-assets/cleanup', { method: 'POST', body: payload || {} }),
   promoteAdminTemplateItem: (itemId, payload) =>
     request(`/api/admin/custom-items/${encodeURIComponent(itemId)}/promote`, { method: 'POST', body: payload }),
+  replaceAdminCustomItem: (itemId, payload) =>
+    request(`/api/admin/custom-items/${encodeURIComponent(itemId)}/replace`, { method: 'POST', body: payload }),
   updateAdminCustomItemLabel: (itemId, payload) =>
     request(`/api/admin/custom-items/${encodeURIComponent(itemId)}/label`, { method: 'PATCH', body: payload }),
   promoteAdminTierListItems: (tierListId, payload) =>