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/ViewModels/Islands/TasksIslandViewModel.cs

@@ -47,6 +47,19 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
     private readonly System.Timers.Timer _reconcileTimer = new(4_000);
 
     public event EventHandler? SelectionChanged;
+
+    /// <summary>Why the selection last changed. Recorded with the detail-pane bind, so the timing
+    /// log attributes rebind churn to a trigger instead of leaving an anonymous count.</summary>
+    public string SelectionSource { get; private set; } = "init";
+
+    /// <summary>Sets <see cref="SelectedTask"/> and tags what triggered it — use this instead of
+    /// assigning the property, otherwise the bind is logged as "?" .</summary>
+    public void SelectFrom(TaskRowViewModel? row, string source)
+    {
+        SelectionSource = source;
+        SelectedTask = row;
+    }
+
     public event EventHandler? FocusAddTaskRequested;
     public event EventHandler? TasksChanged;
     public event Action? NotesRequested;
@@ -57,7 +70,7 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
     [RelayCommand]
     private void OpenNotes()
     {
-        SelectedTask = null;
+        SelectFrom(null, "notes");
         NotesRequested?.Invoke();
     }
 
@@ -359,7 +372,7 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
         HasCompleted  = false;
         ShowOpenLabel = false;
         ShowNotesRow  = false;
-        if (listChanged) SelectedTask = null;
+        if (listChanged) SelectFrom(null, "list-change");
         if (list is null) { IsLetClaudeVisible = false; IsQuickClaudeVisible = false; LoadTask = Task.CompletedTask; return; }
 
         HeaderTitle = list.Name;
@@ -772,7 +785,7 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
         row.ShowListChip = _currentList?.Kind == ListKind.Virtual;
         Items.Add(row);
         Regroup();
-        SelectedTask = row;
+        SelectFrom(row, "new-task");
         NewTaskTitle = "";
         UpdateSubtitle();
         TasksChanged?.Invoke(this, EventArgs.Empty);
@@ -1272,7 +1285,7 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
         row is null ? Task.CompletedTask : SetScheduledForAsync(row, null);
 
     [RelayCommand]
-    private void Select(TaskRowViewModel row) => SelectedTask = row;
+    private void Select(TaskRowViewModel row) => SelectFrom(row, "row-click");
 
     public async System.Threading.Tasks.Task<bool> SelectByIdAsync(string taskId)
     {
@@ -1282,7 +1295,7 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
         }
         var row = Items.FirstOrDefault(r => r.Id == taskId);
         if (row is null) return false;
-        SelectedTask = row;
+        SelectFrom(row, "select-by-id");
         return true;
     }