fix(ui): wire details-island buttons and drop dead handlers

- Bind star button to ToggleStarCommand; wrap header and subtask
  done-check ellipses in buttons (ToggleDone / ToggleSubtaskDone).
- Wire AgentStrip copy-path button to clipboard handler.
- Remove dead Notes/PromptInput/ApproveMerge/ShowWorktreeModal code
  with no UI bindings.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/ClaudeDo.Ui/Views/Islands/AgentStripView.axaml.cs

@@ -1,8 +1,19 @@
 using Avalonia.Controls;
+using Avalonia.Input.Platform;
+using Avalonia.Interactivity;
+using ClaudeDo.Ui.ViewModels.Islands;
 
 namespace ClaudeDo.Ui.Views.Islands;
 
 public partial class AgentStripView : UserControl
 {
     public AgentStripView() { InitializeComponent(); }
+
+    private async void OnCopyWorktreePathClick(object? sender, RoutedEventArgs e)
+    {
+        if (DataContext is not DetailsIslandViewModel vm) return;
+        var clipboard = TopLevel.GetTopLevel(this)?.Clipboard;
+        if (clipboard is null || string.IsNullOrEmpty(vm.WorktreePath)) return;
+        await clipboard.SetTextAsync(vm.WorktreePath);
+    }
 }