feat(ui): wire merge-aware approve and preview into the worker client

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/ClaudeDo.Ui/ViewModels/Islands/DetailsIslandViewModel.cs

@@ -1365,7 +1365,7 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
         // The hub rejects (HubException) if the task is no longer WaitingForReview
         // — e.g. after "Merge all" folded the parent. Swallow it; the TaskUpdated
         // broadcast reconciles the UI. An unhandled command exception would crash.
-        try { await _worker.ApproveReviewAsync(Task.Id); }
+        try { await _worker.ApproveReviewAsync(Task.Id, SelectedMergeTarget ?? ""); }
         catch { /* stale review action; broadcast reconciles */ }
     }