refactor(ui): harden context menu event handling and simplify bindings

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

src/ClaudeDo.Ui/ViewModels/TaskListViewModel.cs

@@ -74,8 +74,6 @@ public partial class TaskListViewModel : ViewModelBase
     [RelayCommand(CanExecute = nameof(CanAddTask))]
     private async Task AddTask()
     {
-        if (CurrentListId is null) return;
-
         // Get list default commit type
         var list = await _listRepo.GetByIdAsync(CurrentListId);
         var defaultCommitType = list?.DefaultCommitType ?? "chore";