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/DetailsIslandViewModel.cs

@@ -578,7 +578,7 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
 
     public void ShowNotes()
     {
-        Bind(null);
+        Bind(null, "notes");
         IsPrepMode = false;
         IsNotesMode = true;
         _ = Notes.LoadDayAsync(DateOnly.FromDateTime(DateTime.Today));
@@ -586,13 +586,15 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
 
     public void ShowPrep()
     {
-        Bind(null);
+        Bind(null, "prep");
         IsNotesMode = false;
         IsPrepMode = true;
         _ = Prep.LoadLastPrepLogIfEmptyAsync();
     }
 
-    public void Bind(TaskRowViewModel? row)
+    /// <param name="source">What triggered the selection (<see cref="TasksIslandViewModel.SelectionSource"/>);
+    /// logged with the bind timing so rebind churn can be attributed to a trigger.</param>
+    public void Bind(TaskRowViewModel? row, string source = "?")
     {
         IsNotesMode = false;
         IsPrepMode = false;
@@ -634,10 +636,10 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
         // agent output, so the Output tab would open empty -- its work shows up as git changes.
         SelectedTab = row.IsManual || row.HasInteractiveSession ? "git" : "output";
 
-        _ = BindAsync(row, ct);
+        _ = BindAsync(row, ct, source);
     }
 
-    private async System.Threading.Tasks.Task BindAsync(TaskRowViewModel row, CancellationToken ct)
+    private async System.Threading.Tasks.Task BindAsync(TaskRowViewModel row, CancellationToken ct, string source)
     {
         var sw = System.Diagnostics.Stopwatch.StartNew();
         var ok = false;
@@ -735,7 +737,7 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
             ok = true;
         }
         catch (OperationCanceledException) { }
-        finally { OperationTiming.Shared.Record("db", "DetailsIsland.BindAsync", sw.Elapsed, ok); }
+        finally { OperationTiming.Shared.Record("db", $"DetailsIsland.BindAsync:{source}", sw.Elapsed, ok); }
     }
 
     private async System.Threading.Tasks.Task LoadChildOutcomesAsync(string parentTaskId, CancellationToken ct)