The candidates hoping to represent New York’s 12th Congressional District sat shoulder-to-shoulder in a wood-paneled room on the fifth floor of the New York Society for Ethical Culture, a white stone building just off Central Park. They squirmed in their seats as the temperature outside hit 95, waiting for an unscreened Q&A from the nicest no-nonsense crowd on the Upper West Side: members of the League of Women Voters. Jack Schlossberg, the grandson of President John F. Kennedy, stretched out