PARIS — It’s 1:00 a.m. on the banks of the Canal de Saint-Denis and the 2024 Paris Olympics closing ceremony finished an hour ago.But in a fan-zone that lines a highway overpass near the Stade de France, Parisian DJ Sara Zinger is pumping out banger after banger for the young crowd of hipsters, tourists and volunteers that's squeezing every last drop of good vibes from these Games. They know that no matter their bedtime, France is about to wake up from its Olympic dream to a harsh reality."The Olympics helped bring people together and everybody was behind the French athletes whether they were Black or white," said Mary Mathurin, 21, a student soaking up the dregs of this sporting festival. "But as soon as we stop focusing on the sports, people are going to start arguing with each other again."The Olympics have been more successful than Paris could have ever imagined, transforming this famously brusque city into an oasis of smiles. They’ve given this fractured nation a genuine moment of...