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/Islands/DetailsIslandView.axaml

@@ -160,7 +160,7 @@
                       Command="{Binding Prep.PlanDayCommand}"
                       IsEnabled="{Binding Prep.IsPlanDayEnabled}"
                       Content="{loc:Tr details.planDay}"/>
-              <ctl:OperationIndicator DataContext="{Binding Prep.PrepOperation}"/>
+              <ctl:OperationIndicator Status="{Binding Prep.PrepOperation}"/>
             </StackPanel>
           </Border>
           <Panel>