feat(ui): replay run log in session terminal, drop per-row live tail

Set the task's log path when the run is created (not at completion) so the
session terminal can replay live output when the user navigates away and back
mid-run. Remove the now-redundant inline per-row live tail (LiveTail /
HasLiveTail / TaskMessageEvent) and scroll the terminal to end after the next
layout pass so wrapping lines aren't clipped.

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

@@ -1,6 +1,5 @@
 using System.Collections.Specialized;
 using Avalonia.Controls;
-using Avalonia.Threading;
 using ClaudeDo.Ui.ViewModels.Islands;
 
 namespace ClaudeDo.Ui.Views.Islands;
@@ -9,16 +8,29 @@ public partial class SessionTerminalView : UserControl
 {
     public SessionTerminalView() { InitializeComponent(); }
 
+    private DetailsIslandViewModel? _boundVm;
+
     protected override void OnDataContextChanged(EventArgs e)
     {
         base.OnDataContextChanged(e);
-        if (DataContext is DetailsIslandViewModel vm)
-            vm.Log.CollectionChanged += OnLogChanged;
+        if (_boundVm is not null)
+            _boundVm.Log.CollectionChanged -= OnLogChanged;
+        _boundVm = DataContext as DetailsIslandViewModel;
+        if (_boundVm is not null)
+            _boundVm.Log.CollectionChanged += OnLogChanged;
     }
 
     private void OnLogChanged(object? sender, NotifyCollectionChangedEventArgs e)
     {
         if (e.Action != NotifyCollectionChangedAction.Add) return;
-        Dispatcher.UIThread.Post(() => LogScroll.ScrollToEnd(), DispatcherPriority.Background);
+        // Scroll after the next layout pass so the freshly-added (wrapping) line
+        // is measured first — otherwise ScrollToEnd stops short and clips it.
+        EventHandler? handler = null;
+        handler = (_, _) =>
+        {
+            LogScroll.LayoutUpdated -= handler;
+            LogScroll.ScrollToEnd();
+        };
+        LogScroll.LayoutUpdated += handler;
     }
 }