LAS VEGAS, Nevada — The person who authorities believe died in the explosion of a Tesla Cybertruck packed with firework mortars and camp fuel canisters outside President-elect Donald Trump’s Las Vegas hotel was an active-duty U.S. Army soldier, three U.S. officials told The Associated Press on Thursday. Two law enforcement officials identified the man inside the futuristic-looking pickup truck as Matthew Livelsberger. The law enforcement officials spoke to the AP on the condition of anonymity because they were not authorized to discuss an ongoing investigation. Three U.S. officials said Livelsberger was an active-duty Army member, who spent time at the