feat: Add character-dialog shortcode and stylesheet

There has been a massive uptick in spam within the past two weeks. A
form field called `_gotcha` is a little on-the-nose, so as a first pass
effort, rename the field to something that sounds more legitimate for a
contact form. More involved strategies will be put in place, but this is
a quick and dirty fix that is worth a try based on the time involved.

layouts/partials/scrolling-image-header.html

@@ -1,6 +1,6 @@
 {{ $thumbnailImage := .Resources.GetMatch "*thumbnail*" }}
 {{ with $thumbnailImage }}
-  {{ $croppedImage := $thumbnailImage.Fill "960x320 center" }}
+  {{ $croppedImage := $thumbnailImage.Fill "1500x500 center" }}
 <style>
   .motto::before {
     background-image: url('{{ $croppedImage.Permalink }}');