feat: markdown in email body for mailing and transactional

templates/admin/system/email_text/_form.html.twig

@@ -4,6 +4,8 @@
     {{ form_row(form.headline) }}
     {{ form_row(form.body) }}
 
+    {{ include('_partials/_markdown_hint.html.twig') }}
+
     <div class="bg-gray-100 rounded-md p-4 text-sm">
         <div class="font-bold pb-2">
             Verfügbare Platzhalter

templates/admin/system/email_text/_preview.html.twig

@@ -6,9 +6,9 @@
     {% if text.headline is not empty %}
         <h1 class="text-xl font-bold pb-2">{{ text.headline | raw }}</h1>
     {% endif %}
-    {# The paragraphs come from the mail body, where email/layout.html.twig styles every
-       <p> with padding-bottom:16px - pb-4 is the same spacing, so the preview matches. #}
-    <div class="[&>p]:pb-4 [&_a]:underline">
+    {# .mail-body carries the spacing and list styling of email/layout.html.twig, so this
+       pane and the mailing pane both show what the mail will look like. #}
+    <div class="mail-body">
         {{ text.bodyHtml | raw }}
     </div>
     <p>