SAN FRANCISCO—Tesla Inc Chief Executive Elon Musk on Thursday said the electric automaker will probably launch a “Tesla Bot” humanoid robot prototype next year, designed for dangerous, repetitive, or boring work that people don’t like to do. Speaking at Tesla’s AI Day event, the billionaire entrepreneur said the robot, which stands around 5-foot-8-inches tall, would be able to handle jobs from attaching bolts to cars with a wrench, or picking up groceries at stores. The robot would have “profound implications for the economy,” Musk said, addressing a labor shortage. He said it was important to make the machine not “super-expensive.” The AI Day event came amid growing scrutiny over the safety and capability of Tesla’s “Full Self-Driving” advanced driver assistant system. Musk didn’t comment on that scrutiny over the safety of Tesla technology. U.S. safety regulators earlier this week opened an investigation into Tesla’s driver assistant system because of accidents …