feat(mission-control): show running Worker operations in a Running now section

Registry of active verify/merge/rebase/worktree-creation operations in the Worker,
GetActiveOperations snapshot + OperationStarted/OperationEnded hub events, and a
Running now section in Mission Control with ticking elapsed time.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/ClaudeDo.Ui/Views/MissionControl/MissionControlView.axaml.cs

@@ -40,6 +40,24 @@ public partial class MissionControlView : UserControl
         OverviewGrid.AddHandler(PointerReleasedEvent, OnTilePointerReleased);
     }
 
+    // Ticks the "Running now" elapsed times while the view is on screen.
+    private Avalonia.Threading.DispatcherTimer? _elapsedTimer;
+
+    protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
+    {
+        base.OnAttachedToVisualTree(e);
+        _elapsedTimer = new Avalonia.Threading.DispatcherTimer { Interval = TimeSpan.FromSeconds(1) };
+        _elapsedTimer.Tick += (_, _) => _vm?.TickOperations();
+        _elapsedTimer.Start();
+    }
+
+    protected override void OnDetachedFromVisualTree(VisualTreeAttachmentEventArgs e)
+    {
+        _elapsedTimer?.Stop();
+        _elapsedTimer = null;
+        base.OnDetachedFromVisualTree(e);
+    }
+
     private const double DragThreshold = 4;
 
     /// <summary>Tile presenter whose header was pressed; null when no tile drag is pending.</summary>
@@ -199,7 +217,7 @@ public partial class MissionControlView : UserControl
     {
         if (e.PropertyName == nameof(MissionControlViewModel.ColumnCount))
             RebuildOverviewGrid();
-        else if (e.PropertyName == nameof(MissionControlViewModel.HasQueued))
+        else if (e.PropertyName == nameof(MissionControlViewModel.HasActivity))
             UpdateQueueColumn();
         else if (e.PropertyName == nameof(MissionControlViewModel.IsFocusMode))
             // The now-visible layout's hosts must re-steal their pane views from the hidden
@@ -221,7 +239,7 @@ public partial class MissionControlView : UserControl
     private void UpdateQueueColumn()
     {
         var queueColumn = BodyGrid.ColumnDefinitions[2];
-        if (_vm?.HasQueued == true)
+        if (_vm?.HasActivity == true)
         {
             queueColumn.MinWidth = MinQueueWidth;
             queueColumn.Width = _queueWidth;