Production at Tesla’s Chinese plant. SHANGHAI (Reuters) – Tesla Inc. plans to start painting at a new plant in Shanghai next month as part of a plan to more than double production capacity in China to meet growing demand for its cars in the country and export markets, two others told Reuters people familiar with the matter. Once the new plant is fully operational, Tesla will have the capacity to produce up to 2 million cars a year at its expanded Shanghai plant, the company’s main export hub, according to people who asked to be known in still-personal talks. The…