Turn on PUZZLES_SHOW_CURSOR on KaiOS

Most KaiOS devices are primarily keyboard-based, so this seems like a
reasonable approach.

I've also switched to specifying boolean values as JSON booleans because
that works now.

kaios/apppage.pl

@@ -20,7 +20,8 @@ print <<EOF;
 <!-- Override some defaults for small screens -->
 <script id="environment" type="application/json">
 { "PATTERN_DEFAULT": "10x10",
-  "PUZZLES_ALLOW_CUSTOM": "N" }
+  "PUZZLES_ALLOW_CUSTOM": false,
+  "PUZZLES_SHOW_CURSOR": true }
 </script>
 <style class="text/css">
 body {