When a French house decides to cross the pond for New York Fashion Week and show its collection in the spiral of the Guggenheim Museum, everything must be right. Nobody wants to look up that famous rotunda and see logos marching down the ramp or, for that matter, navy blazers and khakis. Although the Guggenheim once held a fashion exhibition for Giorgio Armani — and came under heavy criticism — it has never allowed a runway show, until last night.