BEIJING – The abrupt resignation of Nvidia chief executive Jensen Huang has raised fresh questions about China’s access to advanced American artificial intelligence chips, with Beijing accusing Washington of using espionage allegations to justify tighter technology restrictions even as Chinese analysts play down the potential fallout.Huang, who personally lobbied US President Donald Trump to ease restrictions on chip sales to China, was among the most vocal advocates for keeping American technology flowing to the world’s second-largest economy.His departure now threatens to weaken that voice in Washington at a time when US lawmakers are pressing for stricter controls on China’s access…