fix(ui): stop the reconcile tick on native close, index rows in the tick

Two follow-ups to the Phase 3 reconcile tick:

- LogVisualizer and WorktreesOverview only stopped their timer in the Close
  command, but ShowLogVisualizerAsync/ShowWorktreesOverviewAsync had no
  dlg.Closed fallback (unlike the MergeHelper picker). An Alt+F4 or owner
  close left a 4s timer polling the worker / re-running LoadAsync on an
  orphaned VM, accumulating one per open. Extracted StopReconcileTick on both
  VMs and wired it from Closed.
- The tick scanned Items linearly per id; at the 500-row cap that is ~250k
  string comparisons every few seconds. Index the rows once instead.

src/ClaudeDo.Ui/Views/WindowDialogService.cs

@@ -107,6 +107,7 @@ public sealed class WindowDialogService : IDialogService
     {
         var dlg = new WorktreesOverviewModalView { DataContext = vm };
         vm.CloseAction = () => dlg.Close();
+        dlg.Closed += (_, _) => vm.StopReconcileTick();   // native close bypasses CloseCommand
         vm.JumpToTaskAction = (listId, taskId) =>
         {
             if (Shell is { } s) _ = JumpToTaskHelper.SelectAsync(s, listId, taskId);
@@ -161,6 +162,7 @@ public sealed class WindowDialogService : IDialogService
     {
         var dlg = new LogVisualizerView { DataContext = vm };
         vm.CloseAction = () => dlg.Close();
+        dlg.Closed += (_, _) => vm.StopReconcileTick();   // native close bypasses CloseCommand
         await dlg.ShowDialog(_owner);
     }