DoorDash Inc. is partnering with sidewalk-robot developer Serve Robotics Inc. for autonomous deliveries across the US, adding to an array of methods the company is exploring to complement human couriers.Serve’s robots will fulfill some DoorDash orders through a multiyear partnership, starting in Los Angeles, the companies said Thursday in a statement shared with Bloomberg News. Serve, which also counts DoorDash rival Uber Technologies Inc. as a partner, has completed tens of thousands of deliver...