test: fix group sync test mocks to match API format

tests/unit/services/group-sync.test.ts

@@ -15,11 +15,14 @@ describe('GroupSyncService', () => {
     // Setup mock fetch
     fetchMock = mock(async () => ({
       ok: true,
-      json: async () => [
+      json: async () => ({
+        status: 'success',
+        response: [
           { id: 'group1', subject: 'Group 1', linkedParent: 'test-community' },
           { id: 'group2', subject: 'Group 2', linkedParent: 'other-community' },
           { id: 'group3', subject: 'Group 3' } // No linkedParent
         ]
+      })
     }));
     globalThis.fetch = fetchMock;
 
@@ -86,7 +89,8 @@ describe('GroupSyncService', () => {
     it('should handle API errors', async () => {
       globalThis.fetch = mock(async () => ({
         ok: false,
-        statusText: 'Not Found'
+        statusText: 'Not Found',
+        json: async () => ({ status: 'error', message: 'Not Found' })
       }));
       await expect(GroupSyncService.syncGroups()).rejects.toThrow('API request failed: Not Found');
     });