Former Baidu Inc. executive Qi Lu has been named head of Y Combinator China, marking the American startup incubator’s first full-fledged international effort. Y Combinator, which has seeded companies including Airbnb Inc., Stripe Inc., Reddit and Dropbox Inc., will start its program in China as soon as next summer. In the U.S., the accelerator selects two batches of companies a year for financing, advice and connections in exchange for a small percentage of equity.