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.

scripts/test-api.js

@@ -163,6 +163,7 @@ const MENU = {
     items: [
       { value: 'category.createUnderParent', label: 'createUnderParent', hint: 'googleAuthId, parentId, name → row' },
       { value: 'category.rename', label: 'rename', hint: 'googleAuthId, id, name → row' },
+      { value: 'category.order', label: 'order', hint: 'googleAuthId, parentId, JSON categoryIds' },
       { value: 'category.delete', label: 'delete', hint: 'googleAuthId, id' },
       { value: 'category.getTreeForCompany', label: 'getTreeForCompany', hint: 'googleAuthId, companyId → rows' },
       { value: 'category.getCategoryArticles', label: 'getCategoryArticles', hint: 'googleAuthId, categoryId → rows' },
@@ -670,6 +671,33 @@ async function runMethod(client, action) {
         }),
       ];
     }
+    case 'category.order': {
+      const googleAuthId = await askInt('google_auth id');
+      if (googleAuthId == null) return;
+      const parentId = await askInt('parent id');
+      if (parentId == null) return;
+      const categoryIdsJson = await askText('categoryIds JSON', {
+        placeholder: '[2,4,3,5]',
+        validate: (v) => {
+          if (!v?.trim()) return 'Required';
+          try {
+            const parsed = JSON.parse(v);
+            if (!Array.isArray(parsed)) return 'Must be a JSON array';
+          } catch {
+            return 'Invalid JSON';
+          }
+        },
+      });
+      if (categoryIdsJson == null) return;
+      return [
+        'result',
+        await client.category.order({
+          googleAuthId: Number(googleAuthId),
+          parentId: Number(parentId),
+          categoryIds: JSON.parse(categoryIdsJson),
+        }),
+      ];
+    }
     case 'category.delete': {
       const googleAuthId = await askInt('google_auth id');
       if (googleAuthId == null) return;