Thanks to a reworked menu and long hours, Jeannie Kim managed to keep her San Francisco restaurant alive during the coronavirus pandemic. That makes it all the more frustrating that she fears her breakfast-focused diner could be ruined within months by new rules that could make one of her top menu items — bacon — hard to get in California. “Our number one seller is bacon, eggs and hash browns,” said Kim, who for 15 years has run SAMS American Eatery on the city’s busy Market Street. “It could be devastating for us.” At the beginning of next year, California...