PARIS — I’ve heard the word “restart” enough times this season for it to define fashion’s state of mind at the moment. But for Demna at Balenciaga, “restart” also comes with an added psychological weight. Call it reputational rehab. He’s not only clawing his own way back from the damage done by the outrage that erupted in December around two of Balenciaga’s advertising campaigns. “Worse for me was Cristóbal’s name being…