With legs outstretched as one with a six-foot-nine body is inclined to prefer, he was here for one thing. And Rudy Gay, the Baltimore native and 13-year pro basketball veteran due for a new contract, sat on a red plastic chair in an air-conditioned classroom on the tony campus of Park School, the century-old private pre-kindergarten through 12th-grade establishment in the suburban Pikesville hills just north of the city line. on a hot Sunday afternoon, only about four hours until the official opening of the NBA’s free agency signing period-when players not under contract can decide which team they want to head to next.