Federal regulators have for the first time banned a digital platform from serving users under 18, accusing the app — known as NGL — of exaggerating its ability to use artificial intelligence to curb cyberbullying in a groundbreaking settlement.An app popular among children and teens, NGL aggressively marketed to young users despite risks of bullying on the anonymous messaging site, the Federal Trade Commission and the Los Angeles District Attorney’s Office alleged in a complaint unveiled Tuesday...