feat(ui): Review-Merge-Button — Claude nimmt Waiting-for-Review pro Liste ab

Neuer Button in der virtuellen Review-Liste: öffnet das Merge-Helper-Auswahlmodal
im Review-Modus (alle WaitingForReview-Tasks repo-verknüpfter Listen, gruppiert
unter Listen-Headern, alle vorgetickt) und startet pro gewählter Liste eine
ConPTY-Handler-Session direkt in der Merge-Phase — via bestehendem Handoff-Spec
(nextPhase "merge"), kein Triage/Wait davor. Handler-Host-Task wie beim vollen
"Let Claude handle it"-Lauf (HandlerBaseCommit, IsManual).

src/ClaudeDo.Ui/ViewModels/IslandsShellViewModel.cs

@@ -357,6 +357,11 @@ public sealed partial class IslandsShellViewModel : ViewModelBase, IDisposable
             OpenMissionControl();
             _ = MissionControl.OpenMergeHelperConPtySessionAsync(req.ListId, req.TaskIds);
         };
+        Lists.MergeReviewsRequested += req =>
+        {
+            OpenMissionControl();
+            _ = MissionControl.OpenMergeReviewConPtySessionAsync(req.ListId, req.TaskIds);
+        };
         Tasks.TasksChanged     += (_, _) => _ = Lists.RefreshCountsAsync();
         Tasks.OpenListSettingsRequested += (_, _) =>
         {
@@ -368,6 +373,7 @@ public sealed partial class IslandsShellViewModel : ViewModelBase, IDisposable
             if (Lists.SelectedList is { } row)
                 Lists.LetClaudeHandleListCommand.Execute(row);
         };
+        Tasks.MergeReviewsRequested += (_, _) => Lists.MergeReviewsCommand.Execute(null);
         Details.ErrorReported += FlashFooterError;
         Details.CloseDetail = () => Tasks.SelectFrom(null, "close-detail");
         Details.DeleteFromList = row =>