The directive was simple: Stay ready for a last-minute opportunity. Belmont resident Katherine Murphy didn’t think it would work out the way it did. In need of an outfielder ahead of the Women’s Pro Baseball League (WPBL) inaugural opening weekend, the New York Heights phoned the 19-year-old with an urgent message. “Get to Springfield, Illinois, as fast as you can.” “I kind of just dropped everything,” said Murphy, a member of Belmont High School’s Class of 2025. A flight from Boston to St. Louis, Missouri, and a 90 minute drive landed her in Springfield in time for a few practices