Just after lunchtime on a Saturday in November, a sea of purple braids bobs in unison, barely clearing the tops of the movie-theater seats behind them. The high-pitched voices emerging from the violet-coiffed children sing softly at first, crescendoing as the animated character they’re dressed as bares her soul: “No more hiding/ Now I’m shining/ Like I’m born to be!” But it’s not just the kids whose attention is rapt. When the next song begins, a father announces, “This one’s my favorite,” and