feat(ui): scaffold islands shell and child VMs

src/ClaudeDo.Ui/ViewModels/IslandsShellViewModel.cs

@@ -0,0 +1,33 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using ClaudeDo.Ui.ViewModels.Islands;
+
+namespace ClaudeDo.Ui.ViewModels;
+
+public sealed partial class IslandsShellViewModel : ViewModelBase
+{
+    public ListsIslandViewModel Lists { get; }
+    public TasksIslandViewModel Tasks { get; }
+    public DetailsIslandViewModel Details { get; }
+
+    [ObservableProperty]
+    private double _windowWidth = 1280;
+
+    public bool ShowDetails => WindowWidth >= 1100;
+    public bool ShowLists => WindowWidth >= 780;
+
+    partial void OnWindowWidthChanged(double value)
+    {
+        OnPropertyChanged(nameof(ShowDetails));
+        OnPropertyChanged(nameof(ShowLists));
+    }
+
+    public IslandsShellViewModel(
+        ListsIslandViewModel lists,
+        TasksIslandViewModel tasks,
+        DetailsIslandViewModel details)
+    {
+        Lists = lists; Tasks = tasks; Details = details;
+        Lists.SelectionChanged += (_, _) => Tasks.LoadForList(Lists.SelectedList);
+        Tasks.SelectionChanged += (_, _) => Details.Bind(Tasks.SelectedTask);
+    }
+}