Photo: Peter Ash Lee/Art Partner Licensing/Trunk Archive Yerin Ha, breakout star of Bridgerton ’s fourth season , strolls into Koryo Books on a frigid afternoon in February and asks, “Why haven’t I been here before?” Bundled in a full-length black puffer, gray scarf, and black baseball cap for the short walk from her hotel, the 28-year-old Australian actress and I had just met at the entrance of one of the oldest bookstores in New York’s Koreatown. She looks around, delighted. “Ooh, sticker