From lumbering six-foot machines to nimble back-flipping dogs, robots lorded over China’s most important annual AI conference in Shanghai this week. Thousands turned up to gawk at the antics of a bewildering array of droids at work: dispensing popcorn and drinks (messily), peeling eggs, sparring in a boxing ring, playing mahjong or just wandering around the cavernous exhibition hall.The more popular robots were the creations of Unitree, UBTech Robotics Corp. and Agibot, who’ve built up some name...