Shanghai Bistro   Refined and relaxed at the same time, this beautifully appointed second-floor restaurant presents chef Chih-Chieh Chang's version of Asian fusion, combining elements of Chinese, Japanese and southeast Asian cuisines, with some Western touches. Honey walnut shrimp becomes an appetizer of salad greens layered with the shrimp in their mayonnaisy sauce and topped with sugared walnuts. High-design presentation plates and garnishes add to the effect.  Discovery Bay Center, 1778 Ala Moana, second floor. 955-8668. 11 a.m.-10 p.m. daily. Reservations recommended. MC, VS. No checks. $$.