feat(ui): details island with agent strip, terminal, subtasks, notes

Adds AgentStripView (status/model/turns/tokens row, worktree path,
branch line, action buttons), SessionTerminalView (scrollable log with
auto-scroll on CollectionChanged, prompt TextBox with Enter binding),
and replaces DetailsIslandView placeholder with full ScrollViewer layout
containing editable title, agent strip, terminal, subtasks, notes.

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

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

@@ -0,0 +1,23 @@
+using System.Collections.Specialized;
+using Avalonia.Controls;
+using ClaudeDo.Ui.ViewModels.Islands;
+
+namespace ClaudeDo.Ui.Views.Islands;
+
+public partial class SessionTerminalView : UserControl
+{
+    public SessionTerminalView() { InitializeComponent(); }
+
+    protected override void OnDataContextChanged(EventArgs e)
+    {
+        base.OnDataContextChanged(e);
+        if (DataContext is DetailsIslandViewModel vm)
+            vm.Log.CollectionChanged += OnLogChanged;
+    }
+
+    private void OnLogChanged(object? sender, NotifyCollectionChangedEventArgs e)
+    {
+        if (e.Action == NotifyCollectionChangedAction.Add)
+            LogScroll.ScrollToEnd();
+    }
+}