feat(ui): collapse parent task rows by default with granular row sync

tests/ClaudeDo.Ui.Tests/ViewModels/TasksIslandRegroupTests.cs

@@ -168,6 +168,9 @@ public class TasksIslandRegroupTests : IDisposable
         var vm = BuildViewModel();
         await LoadAndWaitAsync(vm, UserList("list1", "Default"));
 
+        // Parents with children collapse by default; expand to surface the nested child.
+        vm.ToggleExpandCommand.Execute(vm.Items.First(r => r.Id == "p1"));
+
         // Child with Done status under an open Planning parent should NOT go to CompletedItems
         Assert.DoesNotContain(vm.CompletedItems, r => r.Id == "c1");
         // Child should appear nested (IsChild == true) in OpenItems