Seven years after founding a robotics startup in San Francisco, Rajat Bhageria is confronting a daunting new task: building robots without any help from China. Like most US-based robotics firms, Chef Robotics has come to rely heavily on Chinese components to make the robot arms it sells to food manufacturers to automate the assembly of ready-made meals. China’s ability to churn out cheap parts at incomparable volumes has made it an integral source of competitive tech products around the world. But as China has begun to dominate advanced industries from electric vehicles to automated factories, an increasingly protectionist US under…