SWEET DEAL: If Betsey Johnson were a cupcake, what kind would she be? Perhaps a fruity fuchsia tie-dyed one, topped off with pink vanilla icing, white-chocolate pop rocks and multicolored glitter. That’s just what Baked by Melissa, the New York bakery known for its mini treats, has whipped up with Johnson. A select group of editors received quite the sampling Wednesday, along with their invitation to Johnson’s fall runway show. The confections will be sold in packs of 25 for $25 and 50 for $50 during New York Fashion Week on Baked by Melissa’s Web site.