feat(ui): wire redesigned detail island (header + description/steps card + work console)

Replace the long scrolling DetailsIslandView with the new pinned layout: a
separated TaskHeaderBar (trash↔skull, gear), a DescriptionStepsCard (text⇄steps
toggle, Preview = composed prompt), and a pinned WorkConsole (Output/Actions/
Session tabs). The three components now bind to DetailsIslandViewModel; their
scaffolding sample VMs are removed. Drops the old inline sections + AgentStripView.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/ClaudeDo.Ui/Views/Islands/Detail/TaskHeaderBar.axaml.cs

@@ -1,4 +1,7 @@
 using Avalonia.Controls;
+using Avalonia.Input;
+using Avalonia.Input.Platform;
+using ClaudeDo.Ui.ViewModels.Islands;
 
 namespace ClaudeDo.Ui.Views.Islands.Detail;
 
@@ -8,4 +11,12 @@ public partial class TaskHeaderBar : UserControl
     {
         InitializeComponent();
     }
+
+    private async void OnTaskIdTapped(object? sender, TappedEventArgs e)
+    {
+        if (DataContext is not DetailsIslandViewModel vm || vm.Task is null) return;
+        var clipboard = TopLevel.GetTopLevel(this)?.Clipboard;
+        if (clipboard is null) return;
+        await clipboard.SetTextAsync(vm.Task.Id);
+    }
 }