HARRISBURG, Pa. — In his first visit to Pennsylvania of 2024, former President Donald Trump seized on a special counsel’s decision not to charge President Joe Biden for mishandling classified documents while Trump continues to contend with a pending criminal case. Before a crowd of thousands of supporters at the National Rifle Association gathering in Harrisburg, Trump contended he was the victim of unfair treatment. “Biden is not going to be charged,” Trump said. “If he’s not going to be charged, that’s up to them. But then I should not be charged.” He also took shots at Biden’s mental facult…