style(ui): subtasks, notes, details metadata footer

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

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

@@ -22,6 +22,9 @@ public sealed partial class TaskRowViewModel : ViewModelBase
     [ObservableProperty] private int _diffAdditions;
     [ObservableProperty] private int _diffDeletions;
 
+    public DateTime CreatedAt { get; init; }
+    public string CreatedAtFormatted => CreatedAt == default ? "—" : $"Created {CreatedAt:MMM d}";
+
     public IReadOnlyList<string> Tags { get; init; } = Array.Empty<string>();
     public int StepsCount { get; init; }
     public int StepsCompleted { get; init; }
@@ -78,6 +81,7 @@ public sealed partial class TaskRowViewModel : ViewModelBase
             ScheduledFor  = t.ScheduledFor,
             DiffAdditions = add,
             DiffDeletions = del,
+            CreatedAt     = t.CreatedAt,
         };
     }