SAN DIEGO — Thirteen-year-old Mei Lee is an overachieving teenager hiding a supersized secret. When Mei gets anxious, aggravated or angry, she turns into a giant red panda. And yes, panda-monium does ensue. But for UC San Diego graduate Lyon Liew, Mei’s giant red panda problem was nothing less than a massive opportunity. Mei is the star of “Turning Red,” a new Pixar Studios animated film debuting tomorrow on the Disney+ streaming platform. Liew is the film’s lead technical director for simulation, which means he and his team were responsible for making clothes, hair, props and giant red panda …