PARIS — Backstage after her shows, Rei Kawakubo usually dispenses a nod, or at most a tentative handshake, to acknowledge a congratulatory comment, but following Saturday’s presentation, she seemed happy to elaborate on the typically gnomic statement that was offered as the show’s manifesto. Which was this: “A feeling of wanting to go back to the starting point.” Everyone assumed that meant Kawakubo was returning to the Ground Zero…