feat: port cms article detail layout into trade-pro + review minors

- article hero/meta/rich-body/author card/next-story/related sidebar
  per cms news/[slug] design; .pro-article-hero contract preserved
- review minors: back-link & CTA render even with 1-2 posts only;
  specificity comment notation corrected to (0,3,1)/(0,2,1)

Co-Authored-By: Claude Code <noreply@anthropic.com>

themes/trade-pro/pages/article.html

@@ -63,9 +63,10 @@
     {% endif %}
   </div>
 </article>
-{% if tp_related %}
+{% if tp_related or tp_next %}
 <section class="section section--soft sf-tp-article-related">
   <div class="wrap sf-tp-article-side">
+    {% if tp_related %}
     <div class="sf-tp-article-side-box" data-reveal>
       <h3>More news</h3>
       {% for p in tp_related %}
@@ -78,6 +79,7 @@
       </a>
       {% endfor %}
     </div>
+    {% endif %}
     <div class="sf-tp-article-side-cta" data-reveal style="--reveal-i: 1">
       <span class="eyebrow">{{ site.name }}</span>
       <h3>Ready to source with confidence?</h3>