China’s progress in building a modern economy, evident in its kung-fu fighting robots and self-parking cars, is hitting limits as a downturn in its housing industry drags on, small businesses suffer and young people struggle to find jobs.The gap between Chinese leader Xi Jinping’s high-tech, artificial intelligence-driven ambitions and the hard realities of slowing growth is the backdrop for the annual meeting of the country’s largely ceremonial national legislature, the Nation...