The welcome team was in place. A 1:45 a.m., four transit workers scrubbed benches, disinfected stair rails with bleach and washed the grime away from a subway station in Brooklyn. Four uniformed police officers kept watch. Nadav Shahaf, 18, a high school student wearing a black mask and a bright red sweatshirt, came bounding down the stairs and plopped onto a newly cleaned bench. He had it all to himself. He was heading home after a late-night stroll with his girlfriend. “I’m happy we got to this point,” he said. “It’s been a tough journey, but we’ve done a good job as a city, as a community.”