feat(ui): add queueing and scheduling from task row context menu

- Right-click on a task row exposes Send to queue / Remove from queue
  and Schedule for... / Clear schedule actions.
- New virtual:queued list in the sidebar with live count.
- Sidebar counts are now computed (open per list, running, queued,
  review) and refreshed on task- and worker-side events.
- Sending a task to the queue wakes the worker so it starts immediately.

src/ClaudeDo.Ui/ViewModels/IslandsShellViewModel.cs

@@ -52,10 +52,12 @@ public sealed partial class IslandsShellViewModel : ViewModelBase
         Lists = lists; Tasks = tasks; Details = details; Worker = worker;
         Lists.SelectionChanged += (_, _) => Tasks.LoadForList(Lists.SelectedList);
         Tasks.SelectionChanged += (_, _) => Details.Bind(Tasks.SelectedTask);
+        Tasks.TasksChanged     += (_, _) => _ = Lists.RefreshCountsAsync();
         Details.CloseDetail = () => Tasks.SelectedTask = null;
-        Details.DeleteFromList = _ =>
+        Details.DeleteFromList = row =>
         {
             Tasks.LoadForList(Lists.SelectedList);
+            _ = Lists.RefreshCountsAsync();
             return System.Threading.Tasks.Task.CompletedTask;
         };
         Worker.PropertyChanged += (_, e) =>