When an American missile punctured a Chinese spy balloon last week, it was a dramatic symbol of what many have long suspected: the U.S. policy of engagement with China has collapsed as completely as that balloon.  Engagement — the idea that if the U.S. wrapped China in a cocoon with Western economies a more liberal China would emerge — had a hell of a run and scored some big victories over the last half century. China's economic reforms have lifted hundreds of millions of Chinese out