Add category.order to reorder siblings under a parent.

Sets each direct child's sort to its index in the given categoryIds,
scoped by parentId. Validates the set matches the current children.

src/index.js

@@ -9,6 +9,7 @@ import categoryGetTreeForCompany from './store/category/getTreeForCompany.js';
 import categoryGetCategoryArticles from './store/category/getCategoryArticles.js';
 import categoryCreateUnderParent from './store/category/createUnderParent.js';
 import categoryRename from './store/category/rename.js';
+import categoryOrder from './store/category/order.js';
 import categoryDelete from './store/category/delete.js';
 import articleDelete from './store/article/delete.js';
 import articleDeleteImage from './store/article/deleteImage.js';
@@ -73,6 +74,7 @@ export default class LibDashStore {
       getCategoryArticles: categoryGetCategoryArticles(pool),
       createUnderParent: categoryCreateUnderParent(pool),
       rename: categoryRename(pool),
+      order: categoryOrder(pool),
       delete: categoryDelete(pool),
     };