By Samuel L. Leiter April 2, 2026: Stage 42, a 499-seat Off-Broadway theatre, would classify as Broadway if it had one more seat. Gotta Dance!, its engaging new tenant, is a bit shy of Broadway status as well, but that shouldn't stop it from keeping this too infrequently used venue tapping its toes throughout its run. A project of the American Dance Machine, whose mission is to archive the great choreography of Ame…