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/Islands/TaskRowViewModel.cs

@@ -37,6 +37,8 @@ public sealed partial class TaskRowViewModel : ViewModelBase
     public bool HasSteps    => StepsCount > 0;
     public bool IsOverdue   => ScheduledFor is { } d && d.Date < DateTime.Today && !Done;
     public bool IsRunning   => Status == TaskStatus.Running;
+    public bool IsQueued    => Status == TaskStatus.Queued;
+    public bool HasSchedule => ScheduledFor.HasValue;
     public bool HasLiveTail => IsRunning && !string.IsNullOrEmpty(LiveTail);
 
     public string DiffAdditionsText => $"+{DiffAdditions}";
@@ -56,13 +58,18 @@ public sealed partial class TaskRowViewModel : ViewModelBase
     {
         OnPropertyChanged(nameof(StatusChipClass));
         OnPropertyChanged(nameof(IsRunning));
+        OnPropertyChanged(nameof(IsQueued));
         OnPropertyChanged(nameof(HasLiveTail));
     }
 
     partial void OnBranchChanged(string? value)    => OnPropertyChanged(nameof(HasBranch));
     partial void OnLiveTailChanged(string? value)  => OnPropertyChanged(nameof(HasLiveTail));
     partial void OnDoneChanged(bool value)         => OnPropertyChanged(nameof(IsOverdue));
-    partial void OnScheduledForChanged(DateTime? value) => OnPropertyChanged(nameof(IsOverdue));
+    partial void OnScheduledForChanged(DateTime? value)
+    {
+        OnPropertyChanged(nameof(IsOverdue));
+        OnPropertyChanged(nameof(HasSchedule));
+    }
     partial void OnDiffAdditionsChanged(int value) { OnPropertyChanged(nameof(HasDiff)); OnPropertyChanged(nameof(DiffAdditionsText)); }
     partial void OnDiffDeletionsChanged(int value) { OnPropertyChanged(nameof(HasDiff)); OnPropertyChanged(nameof(DiffDeletionsText)); }