Amazon’s (AMZN) dominance in e-commerce makes any potential threat hard to take seriously. On the surface anyway. But the staggering growth of direct shippers like Temu and Shein, though puny in comparison, has grabbed the attention of the people who run the everything store. And Amazon aims to confront them directly before they get much more traction. Amazon’s reported move to start a new service focused on shipping low-cost fashion and lifestyle products directly from China highlights how bargain platforms have made inroads with American shoppers and Chinese manufacturers. And how even market leaders are forced to adjust to maintain…