Trey Lance sustained an injury to his right ankle in the first quarter of the 49ers’ home opener, and the upstart quarterback required a cart to take him into the locker room for further evaluation. The 49ers’ medical staff appeared to place an air cast on Lance’s leg following a collision with linebacker Cody Barton. Lance, making only his fourth career start, was injured when his right leg got trapped under him while he was tackled on a 2-yard zone-read keeper to the Seattle Seahawks’ 19-yard line. Lance was initially helped up by center Jake Brendel before going back down to the turf, writh…