China and the European Commission appeared close to announcing a landmark agreement this week that would make it easier for their companies to invest in each other’s economies. Then it hit another snag: A tweet by a top aide to Joseph R. Biden Jr. signaled that the president-elect was not happy about the deal.The pact, nearly seven years in the making, remains a top priority of Chancellor Angela Merkel of Germany because it would give companies like Daimler and Volkswagen better control over their operations in China.China, which has long been wary of allowing foreign companies greater …
