Stay informed with free updatesSimply sign up to the Artificial intelligence myFT Digest -- delivered directly to your inbox.Stanford University’s artificial intelligence leader Fei-Fei Li has quietly built a billion-dollar start-up in just four months, joining the fierce race across the tech industry to commercialise the technology.Li, a computer scientist who has been dubbed the “godmother of AI”, created a company called World Labs in April, according to three people with knowledge of the mov...