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/Modals/SettingsModalView.axaml

@@ -281,7 +281,7 @@
                 <Button Classes="btn" Content="{loc:Tr settings.files.restoreDefaultAgents}"
                         Command="{Binding Files.RestoreDefaultAgentsCommand}"
                         HorizontalAlignment="Left"/>
-                <ctl:OperationIndicator DataContext="{Binding Files.RestoreOp}"/>
+                <ctl:OperationIndicator Status="{Binding Files.RestoreOp}"/>
               </StackPanel>
               <StackPanel Spacing="6">
                 <TextBlock Classes="section-label" Text="{loc:Tr settings.files.promptsSection}"/>
@@ -504,14 +504,14 @@
                   <Button Grid.Column="1" Classes="btn" Content="{loc:Tr settings.skills.installButton}"
                           Command="{Binding SessionSkills.InstallCommand}"/>
                 </Grid>
-                <ctl:OperationIndicator DataContext="{Binding SessionSkills.InstallOp}"/>
+                <ctl:OperationIndicator Status="{Binding SessionSkills.InstallOp}"/>
               </StackPanel>
 
               <Border BorderBrush="{DynamicResource LineBrush}" BorderThickness="0,1,0,0" Margin="0,2,0,0"/>
 
               <StackPanel Spacing="6">
                 <TextBlock Classes="section-label" Text="{loc:Tr settings.skills.installedSection}"/>
-                <ctl:OperationIndicator DataContext="{Binding SessionSkills.UpdateOp}"/>
+                <ctl:OperationIndicator Status="{Binding SessionSkills.UpdateOp}"/>
                 <ItemsControl ItemsSource="{Binding SessionSkills.Skills}">
                   <ItemsControl.ItemTemplate>
                     <DataTemplate x:DataType="services:SessionSkillDto">