fix(ui): wire delete confirm, close-details, uppercase eyebrow, explorer button

- A1: list-name eyebrow runs through UpperCase converter.
- D2: + Open-in-explorer icon button in AgentStrip (Process.Start on worktree path).
- D4: DeleteTaskCommand prompts inline confirm Window before deleting; shell
  wires Details.CloseDetail to clear Tasks.SelectedTask and Details.DeleteFromList
  to reload the current list.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/ClaudeDo.Ui/ViewModels/IslandsShellViewModel.cs

@@ -42,6 +42,12 @@ public sealed partial class IslandsShellViewModel : ViewModelBase
         Lists = lists; Tasks = tasks; Details = details;
         Lists.SelectionChanged += (_, _) => Tasks.LoadForList(Lists.SelectedList);
         Tasks.SelectionChanged += (_, _) => Details.Bind(Tasks.SelectedTask);
+        Details.CloseDetail = () => Tasks.SelectedTask = null;
+        Details.DeleteFromList = _ =>
+        {
+            Tasks.LoadForList(Lists.SelectedList);
+            return System.Threading.Tasks.Task.CompletedTask;
+        };
         _ = Lists.LoadAsync();
     }
 }