By Nilesh Christopher, Los Angeles TimesThe hottest new gig-economy job in Los Angeles is performing at home to help artificial intelligence understand how humans move. Hundreds of people from Santa Monica to Los Feliz are strapping cameras on their heads and hands as they do chores at home so bots can watch how they make coffee, scrub toilets, water plants and wash dishes. At a corner table at Urth Caffe downtown, a woman is sitting next to a big black bag. A constant flow of visitors stops by. She slips each a package and instructions, and they move on. “People...