Firefighters in Silicon Valley were sent out to enforce statewide business restrictions as the state faced a Thanksgiving shadowed by an out-of-control coronavirus surge and health officials begged people to avoid large family gatherings that could become “superspreader” events. Black Friday sales that typically draw enormous crowds also are in the spotlight. The holiday season leading into Christmas can account for a large chunk of store profits. But stores must follow COVID-19 safety orders such as requiring employees and customers to wear masks and observe social distancing, health officers warned. Compliance officers were to fan out throughout the county starting...