Adrit Rao at the University of California, Berkeley, where he's a freshman.Adrit RaoAdrit Rao, 18, learned how to build apps in middle school by watching YouTube videos.A cold email to a Stanford professor led to a job at the university, though not to admission as a student.Now a freshman at the University of California, Berkeley, he balances classes with a full-time AI job.This as-told-to essay is based on a conversation with Adrit Rao, a fresh…