Restore js-only on queue btn, make + always visible

Reverts removal of js-only class. Changes queue button color from
text-muted to text-primary so it's always clearly visible, not
just on hover.

make_post_sell/static/css/common.css

@@ -2896,7 +2896,7 @@ textarea {
     cursor: pointer;
     font-size: 1.1rem;
     padding: 4px;
-    color: var(--text-muted, #999);
+    color: var(--text-primary, #333);
     border-radius: 50%;
     width: 28px;
     height: 28px;

make_post_sell/templates/snippets/related_content.j2

@@ -21,7 +21,7 @@
             {% endif %}
             <span class="related-content-title">{{ related.title }}</span>
         </a>
-        <button class="queue-add-btn"
+        <button class="queue-add-btn js-only"
                 data-product-id="{{ related.id }}"
                 data-title="{{ related.title }}"
                 data-url="{{ related.absolute_url(request) }}"