HONG Kong tycoon and pro-democracy advocate Jimmy Lai pleaded not guilty in a landmark trial, where he is accused of endangering China's national security, as prosecutors laid out details of what they said was collusion with foreign forces. Lai, a leading critic of the Chinese Communist Party, faces two counts of conspiracy to collude with foreign forces - including calling for sanctions against Hong Kong and Chinese officials - under a China-imposed national security law. "Not guilty," Lai said three times as each charge was read, appearing calm as he sat in a glass dock surrounded by guards and a…