execute method
Deletes a task at the specified index from the column.
Notifies listeners with a TaskRemovedEvent when successful. Returns a Result containing the removed task.
Parameters:
column: The column containing the taskindex: The index of the task to delete
Implementation
Result<Task> execute(KanbanColumn column, int index) {
final removed = column.deleteTask(index);
EventNotifier().notify(TaskRemovedEvent(removed, column));
return Success(removed);
}