A 21-year-old fashion model was nabbed for stealing more than $1 million in high-end designer merchandise from an upscale SoHo retailer — then released without bail. Abdallah Diaby was arrested Thursday and charged in an early morning, caught-on-video heist at the ritzy 4Gseller boutique on Spring Street on Dec. 1, when cops said four masked crooks broke in and made off with 20 St. Laurent designer jackets, 30 handbags, 20 belts and other ritzy goods. Diaby was linked to the break-in through