It was a fitting introduction. Chloé Zhao, director of the Indian-cowboys tale “The Rider” (now playing at the Mayan Theater), was standing on the lobby stairs of the Chuck Jones Cinema about to reach out her hand by way of a hello. Instead, distracted, she kept glancing to her left. Her star, 22-year-old Brady Jandreau, and his best friend, Lane Scott, were making their way down a hallway after the movie was enthusiastically received at the Telluride Film Festival.