fix(claude-do): Fix: Statuswechsel schlägt in Task-Row und Detail-Pane erst

## Problem (vom Nutzer bestätigt am 2026-08-05)
Wechselt ein Task den Status, bleiben zwei Stellen stehen, bis man die Liste wechselt und zurückwechselt:

1. **Task-Row in der offenen Liste** (mittlere Insel) — Status-Chip und Gruppen-Einordnung aktualisieren sich nicht.
2. **Detail-Pane des ausgewählten Tasks** (rechte Insel) — Status, Review-Buttons und Header-Bar zeigen weiter den alten Zustand

ClaudeDo-Task: 181d4abf368046b99bd57d5e2a7ab97a

src/ClaudeDo.Ui/ViewModels/Islands/TasksIslandViewModel.cs

@@ -237,6 +237,12 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
         // the selection so a live update never yanks the detail pane away.
         var listChanged = !string.Equals(_currentList?.Id, list?.Id, StringComparison.Ordinal);
 
+        // A same-list reload (triggered by OnWorkerTaskUpdated's full-reload branches) rebuilds
+        // every row from scratch. Reusing the previous instances by id — instead of handing back
+        // brand new ones — keeps SelectedTask (and the bound DetailsIslandViewModel.Task) pointed
+        // at a live row instead of an orphan that never receives another update.
+        var reusable = listChanged ? null : Items.ToDictionary(r => r.Id);
+
         if (_currentList is not null)
             _currentList.PropertyChanged -= OnCurrentListPropertyChanged;
         _currentList = list;
@@ -261,10 +267,11 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
         IsMyDayList  = list.Id == "smart:my-day";
         IsLetClaudeVisible = list.Kind == ListKind.User && !string.IsNullOrWhiteSpace(list.WorkingDir);
 
-        LoadTask = LoadForListAsync(list, ct);
+        LoadTask = LoadForListAsync(list, ct, reusable);
     }
 
-    private async Task LoadForListAsync(ListNavItemViewModel list, CancellationToken ct)
+    private async Task LoadForListAsync(
+        ListNavItemViewModel list, CancellationToken ct, Dictionary<string, TaskRowViewModel>? reusable)
     {
         try
         {
@@ -292,7 +299,16 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
             var showListChip = list.Kind == ListKind.Virtual;
             foreach (var t in filteredList)
             {
-                var row = TaskRowViewModel.FromEntity(t);
+                TaskRowViewModel row;
+                if (reusable is not null && reusable.TryGetValue(t.Id, out var existing))
+                {
+                    row = existing;
+                    row.UpdateFromEntity(t);
+                }
+                else
+                {
+                    row = TaskRowViewModel.FromEntity(t);
+                }
                 row.ShowListChip = showListChip;
                 row.HasInteractiveSession = _interactiveSessionIds.Contains(row.Id);
                 Items.Add(row);