Microsoft has closed its IoT & AI Insider Lab in Shanghai’s Zhangjiang hi-tech zone, marking the latest sign of the US tech giant’s retreat from China amid rising geopolitical tensions.The Shanghai lab, meant to help with domestic development of the Internet of Things (IoT) and artificial intelligence (AI) technologies, closed earlier this year, according to people who work in the Zhangjiang AI Island area.The lab was dark and unoccupied during a recent visit by the South China Morning Post, wit...