fix(falcon-PS9): prevent 500 error on AJAX filtering by normalizing data

Resolved a Fatal Error occurring during AJAX product listing requests (e.g., price slider).

- Issue: In PHP 8.2+, accessing properties of a 'CategoryLazyArray' object
  using array syntax (dot notation) triggers a Fatal Error.
- Cause: The Faceted Search module returns a LazyArray object during
  XHR requests, whereas standard page loads provide a native array.
- Solution: Implemented a normalization block using JSON serialization
  to flatten the object into a standard associative array. This ensures
  template syntax compatibility regardless of the request type or
  property visibility (protected vs public).

falcon/templates/catalog/_partials/category-footer.tpl

@@ -1,5 +1,13 @@
+{* Defensive: Handles LazyArray objects for category *}
+{if is_object($category)}
+  {$category = $category|json_encode|json_decode:true}
+  {if isset($category.category)}
+    {$category = $category.category}
+  {/if}
+{/if}
+
 <div id="js-product-list-footer">
-    {if $category.additional_description && $listing.pagination.items_shown_from == 1}
+    {if isset($category.additional_description) && $category.additional_description && $listing.pagination.items_shown_from == 1}
       <div id="category-description-2" class="cms-content my-3">
         {$category.additional_description nofilter}
       </div>