feat: add item images, product detail page, and gallery support in catalog

- Added `ItemImage` model with migration for image handling and metadata
- Implemented product gallery in `detail.html` with thumbnails for additional images
- Updated `Item` model to include `primary_image` property for gallery logic
- Enhanced `catalog/index.html` to support item thumbnails
- Updated `catalog.css` for responsive gallery and item list styling
- Extended catalog views to prefetch images for efficient queries
- Added comprehensive tests for catalog and detail views
- Configured Django to serve media files in development
- Updated admin with inline support for managing `ItemImage` entities

templates/catalog/_fragments/side-bar.html

@@ -1,8 +1,13 @@
 <aside>
     <section class="categories a-section">
         <h2>Категории</h2>
+        <a href="/catalog/" class="category {% if selected_category.id == None %}active{% endif %}">Все товары</a>
         {% for category in categories %}
-            <a href="/catalog/{{ category.slug }}" class="category">{{ category.name }}</a>
+            <a href="/catalog/{{ category.slug }}/" class="category {% if selected_category.id == category.slug %}active{% endif %}">
+                {{ category.name }}
+            </a>
+        {% empty %}
+            <p class="categories-empty">Категории пока не добавлены.</p>
         {% endfor %}
     </section>
 
@@ -13,26 +18,22 @@
     <form action="">
         <section class="a-section cost-section">
             <h2>Стоимость</h2>
-
         </section>
 
         <section class="a-section color-section">
             <h2>Цвет</h2>
-
         </section>
 
         <section class="a-section material-section">
             <h2>Материал</h2>
-
         </section>
 
         <section class="a-section promotions-section">
             <h2>Акции</h2>
-
         </section>
 
         <section class="a-section new-section">
             <h2>Новинки</h2>
         </section>
     </form>
-</aside>
+</aside>