NEW YORK — Flanked by stained-glass windows, 54 New York City high school students challenge one another to imagine an ideal democracy. Wood-paneled walls are covered in haphazardly taped posters that students worked together to create. Ideas are written in Crayola marker under categories such as “rights” and “responsibilities.” Some posters are divided down the middle by an imperfect line, separating the students’ hopes and fears for democracy’s future. On one side, their hopes.