The Justice Department accused Chief U.S. District Judge James Boasberg of posing a "mortal threat" to attorney-client privilege as its own lawyers risk criminal contempt charges.The accusation came in a reply brief the department filed Friday with the full U.S. Court of Appeals for the District of Columbia Circuit.The court hears arguments Sept. 29 on whether Boasberg may keep investigating who defied his order to turn deportation flights aroun…