WASHINGTON — Christine Blasey Ford declared today that Brett Kavanaugh sexually assaulted her as he and a friend shared “uproarious laughter” in a locked room at a 1980s high school gathering, recounting her allegations to the Senate Judiciary Committee and a riveted nation in a drama that threatens to derail Kavanaugh’s Supreme Court nomination.Her account, delivered in a soft and sometimes-halting voice, came as the Judiciary panel began an extraordinary session that Republicans hope will let them …