Apple Inc.’s lead artificial intelligence researcher for robotics has departed the company to join Meta Platforms Inc.’s competing effort, part of an exodus of AI talent from the iPhone maker.The employee, Jian Zhang, joined the Meta Robotics Studio, the social media company confirmed on Tuesday. Separately, three more AI researchers are leaving Apple’s in-house large language models team, adding to upheaval in that group, according to people with knowledge of the matter....