During her decades-long career, Mellen left her stylish mark at Harper’s Bazaar, American Vogue and Allure. A tribute for the indomitable fashion editor Polly Mellen, who died Dec. 12, is being planned for this summer in Kent, Conn. Mellen, the longtime sittings and fashion editor at Vogue, passed away at age 100 at the assisted living facility Noble Horizons in…