feat(ui): add reconcile tick to self-heal lost worker broadcasts

TasksIslandViewModel now runs a periodic tick that diffs the flat Items
collection against SQLite and patches properties in place (capped at 500
rows, sharing the Phase 1 delta sequence guard so it never overtakes a
fresher broadcast). Never rebuilds rows or triggers Regroup/LoadForList, so
it stays decoupled from the parallel Phase 2b virtualization work. The same
cadence now refreshes the long-lived Worktrees Overview, Log Visualizer, and
Merge Helper selection overlays; short-lived modals are untouched.

src/ClaudeDo.Ui/Views/MainWindow.axaml.cs

@@ -25,7 +25,11 @@ public partial class MainWindow : Window
     {
         base.OnPropertyChanged(change);
         if (change.Property == WindowStateProperty)
+        {
             UpdateMaxIcon();
+            if (DataContext is IslandsShellViewModel vm && vm.Tasks is not null)
+                vm.Tasks.IsWindowVisible = WindowState != WindowState.Minimized;
+        }
         if (change.Property == OffScreenMarginProperty)
             RootGrid.Margin = OffScreenMargin;
     }
@@ -48,6 +52,8 @@ public partial class MainWindow : Window
                     WindowState = WindowState.Normal;
                 Activate();
             };
+            if (vm.Tasks is not null)
+                vm.Tasks.IsWindowVisible = WindowState != WindowState.Minimized;
         }
     }