GUANTÁNAMO BAY, Cuba — In a first, a military judge at Guantánamo Bay on Friday crossed into the security zone containing the wartime prison and inspected a former CIA “black site” facility at the center of a dispute over the taint of torture in the Sept. 11, 2001, case. It was a noteworthy moment in the arc of the two-decade history of the Guantánamo trials. No war court judge had before made the 5-mile trip to look at the detention operations, where the military maintains the only known, still