fix(dates): add font-mono text-sm to all <time> elements

System convention: every rendered date gets font-mono class.
CSS base layer handles font-family, but classes ensure consistency
and proper text-sm sizing across all templates.

Confab-Link: http://localhost:8080/sessions/0ec83454-d346-4329-8aaf-6b12139bf596

articles.njk

@@ -34,7 +34,7 @@ permalink: "articles/{% if pagination.pageNumber > 0 %}page/{{ pagination.pageNu
         </h2>
       </div>
       <div class="post-meta mt-2">
-        <time class="dt-published" datetime="{{ post.date | isoDate }}">
+        <time class="dt-published font-mono text-sm" datetime="{{ post.date | isoDate }}">
           {{ post.date | dateDisplay }}
         </time>
         {% if post.data.category %}