feat: add favorites feature for users

- Implemented `Favorite` model with unique user-item constraint and timestamped records
- Added `favorites:index` and `favorites:toggle` views with AJAX support for toggling favorites
- Built templates and front-end assets for the favorites page and integration with item grids
- Extended header with favorites link and dynamic counter
- Added tests covering models, views, and templates for the favorites functionality
- Updated admin to enable management of favorites via Django admin interface

templates/_layouts/base.html

@@ -16,6 +16,7 @@
     <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@fancyapps/ui@6.1/dist/fancybox/fancybox.css"/>
     <script src="https://cdn.jsdelivr.net/npm/swiper@12/swiper-bundle.min.js"></script>
     <script src="https://cdn.jsdelivr.net/npm/@fancyapps/ui@6.1/dist/fancybox/fancybox.umd.js"></script>
+    <script src="{% static 'js/header-category-dropdown.js' %}"></script>
     {% block add_css %}
         <!-- Additional CSS -->
     {% endblock %}
@@ -48,9 +49,10 @@
                 closeButton.addEventListener('click', hideToast)
             }
 
-            window.setTimeout(hideToast, 4000)
+        window.setTimeout(hideToast, 4000)
         })
     })
 </script>
+<script src="{% static 'js/favorites.js' %}"></script>
 </body>
 </html>