Beijing whipped out its flashiest gadgets for the 2022 Winter Olympics: Robots flipped burgers and served meals at the canteens, a green cooling system used carbon dioxide to keep ice rinks cold, and smart beds monitored the heart rates and breathing of athletes as they slept.  But in its effort to cement its role as an innovation powerhouse, China’s most ambitious technological debut was also its most controversial: The digital yuan was rolled out as the legal tender of choice for the