fix(ui): unfreeze the operation spinner and attribute rebind churn

Three causes behind the stuck indicator:
- OperationStatus.End did not retire the generation, so tick work posted
  while the dispatcher was blocked drained afterwards and set
  ShowIndicator back to true on a finished operation.
- The startup update check ran in Task.Run; OperationStatus writes its
  observable properties on the calling thread, so the final
  ShowIndicator=false never reached the binding.
- OperationIndicator overwrote its own DataContext from the Status
  property, which re-targeted the call-site binding. It now scopes the
  DataContext to an inner panel and collapses itself when Status is
  null; every call site switched from DataContext= to Status=.

Also gates the footer connection pill in the command body instead of
CanExecute (a disabled command greyed out the ONLINE chip), and extends
OperationTiming: pid per line, 4 MB rollover, fast successes dropped
(failures always kept), and DetailsIsland.BindAsync now carries the
selection trigger via TasksIslandViewModel.SelectFrom.

src/ClaudeDo.Ui/Views/Controls/OperationIndicator.axaml.cs

@@ -15,12 +15,21 @@ public partial class OperationIndicator : UserControl
         set => SetValue(StatusProperty, value);
     }
 
-    public OperationIndicator() => InitializeComponent();
+    public OperationIndicator()
+    {
+        InitializeComponent();
+        IsVisible = false;
+    }
 
+    /// A null `Status` leaves the inner panel's DataContext null, so its `IsVisible="{Binding
+    /// ShowIndicator}"` can't resolve and falls back to the property default — *visible*. That
+    /// renders a label-less spinner plus the stalled hint forever. Collapse the whole control
+    /// instead. Deliberately a direct set, not a binding: no call site binds `IsVisible` on the
+    /// indicator, and a local value would win over one anyway.
     protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
     {
         base.OnPropertyChanged(change);
         if (change.Property == StatusProperty)
-            DataContext = change.GetNewValue<OperationStatus?>();
+            IsVisible = change.GetNewValue<OperationStatus?>() is not null;
     }
 }