WASHINGTON — Mentalist Oz Pearlman was supposed to dazzle an audience of hundreds on Saturday night here with mind tricks in a well-lit hotel ballroom. Instead he found himself doing his act for a small handful of media executives in a darkened underground event space close to midnight. MS NOW had planned to host a festive soirée in the site of an old subterranean trolley station in the heart of the nation’s capital, part of the usual proceedings following the annual White House Correspondents Dinner . This year was going to be more auspicious — until horror struck just hours earlier: Authorities are still investigating an incident in which a man was able to get close to a space in the Washington Hilton where President Donald Trump was to attend — and deliver pointed remarks — to an assemblage of journalists, news executives, media honchos and government officials at a celebration of journalism that is woven into the social calendar of this city devoted to the federal government.…