Bob Baffert was the first trainer to win the Pegasus World Cup Invitational twice. And now, he’s the first to win it three times. National Treasure, the Preakness winner last year, dug deep in the stretch to win the 1⅛-mile Pegasus World Cup at Gulfstream Park on Saturday. The Grade 1, $3 million race is the richest of the year at Gulfstream, and National Treasure — the 5-2 favorite — had to hold off hard-charging Senor Buscador in the stretch run to get the victory…