SAN DIEGO (AP) — The U.S. is seeing a big increase in Chinese immigrants arriving using a relatively new and perilous route through Panama’s Darién Gap jungle, thanks in part to social media posts and videos providing step-by-step guidance. Chinese people were the fourth-highest nationality, after Venezuelans, Ecuadorians and Haitians, crossing the Darién Gap during the first nine months of this year, according to Panamanian immigration authorities. Chinese migrants using this route fly to Ecuador and then make their way north to the U.S.-Mexico border. Chinese migrants interviewed by The Associated Press said they are seeking to escape an increasingly...