If you assumed earlier this year, based on a barrage of dreamy, sun-drenched Instagram posts, that all your favorite French designers — India Mahdavi, Pierre Yovanovitch, Dorothée Meilichzon — seemed to be vacationing in the same idyllic beach town in the French Riviera, you would be almost correct. Actually, they were attending the 16th edition of Design Parade, the French design festival that has become a go-to for spotting new trends and discovering the next wave of buzzy young designers.