MILAN — You’ve got to have art — or at least a little touch of something artsy. That was one of the big messages from the recent Milan collections. Miuccia Prada’s runway was filled with artful effects — a computer-distorted wheat print, imperfect beading and offbeat fabric combinations. Here, Prada’s faux industrial-latex camp shirt and homespun hopsack skirt. For more on Milan, see pages 6 to 9.