feat(ui): add Merge command to DiffModal

src/ClaudeDo.Ui/ViewModels/Modals/DiffModalViewModel.cs

@@ -42,6 +42,10 @@ public sealed partial class DiffModalViewModel : ViewModelBase
 
     public required string WorktreePath { get; init; }
     public string? BaseRef { get; init; }
+    public string? TaskId { get; init; }
+    public string TaskTitle { get; init; } = "";
+    public Func<MergeModalViewModel, Task>? ShowMergeModal { get; set; }
+    public Func<MergeModalViewModel>? ResolveMergeVm { get; set; }
 
     public ObservableCollection<DiffFileViewModel> Files { get; } = new();
 
@@ -58,6 +62,20 @@ public sealed partial class DiffModalViewModel : ViewModelBase
     [RelayCommand]
     private void Close() => CloseAction?.Invoke();
 
+    private bool CanMerge() =>
+        !string.IsNullOrEmpty(TaskId)
+        && ShowMergeModal is not null
+        && ResolveMergeVm is not null;
+
+    [RelayCommand(CanExecute = nameof(CanMerge))]
+    private async Task MergeAsync()
+    {
+        if (TaskId is null || ShowMergeModal is null || ResolveMergeVm is null) return;
+        var vm = ResolveMergeVm();
+        await vm.InitializeAsync(TaskId, TaskTitle);
+        await ShowMergeModal(vm);
+    }
+
     public async Task LoadAsync(CancellationToken ct = default)
     {
         Files.Clear();