By Jeff Mason and Steve Holland VALLEY FORGE, Pennsylvania (Reuters) – Joe Biden on Friday accused Republican Donald Trump, his likely 2024 election opponent, of instigating the Jan. 6 attacks and plotting revenge on those seeking to punish him, as the president put the future of U.S. democracy at the center of his bid for re-election. “He told the crowd to fight like hell. And all hell was unleashed,” Biden said of the 2021 attack. “Then as usual he left the dirty work to others. He retreated to the White House.” Biden marked three years since the Jan. 6, 2021, attacks with his first major ca…