Major ports and foreign trade provinces in China are showing the first signs of disruption from the ongoing tariff war between the world’s two largest economies. Virtually no cargo ships were bound for the U.S. by Thursday from once-bustling ports in Shanghai and Guangdong, while operations at export factories in provinces that feed China’s export empire have ground to a halt, sources in the country said. Stacks of shipping containers that failed to make the ships bound for the U.S. by the April 9 deadline are now piled high at…