feat: add color, discount price, and new item attributes to catalog and update UI

- Introduced `Color` model with admin and added a color field to items
- Added `discount_price` and `is_new` fields to the `Item` model with necessary migrations
- Updated pricing logic to display original and discount prices in templates
- Enhanced product detail and item card templates with color swatches and metadata
- Added sidebar sections for sales and new items with paginated mini-cards
- Updated styles to support discount pricing, swatches, and sidebar mini-cards
- Extended catalog views to filter by sales or new items and updated filtering logic

templates/catalog/detail.html

@@ -43,18 +43,29 @@
             <h1 class="product-summary__title">{{ item.name }}</h1>
 
             <div class="product-summary__meta">
-                <span class="product-summary__price">{{ item.price }} руб.</span>
+                <div class="product-summary__price-block">
+                    <span class="product-summary__price{% if item.has_discount %} product-summary__price--discount{% endif %}">
+                        {{ item.display_price }} руб.
+                    </span>
+                    {% if item.has_discount %}
+                        <span class="product-summary__price-original">{{ item.price }} руб.</span>
+                    {% endif %}
+                </div>
                 <span class="product-summary__availability {% if item.is_available %}available{% else %}unavailable{% endif %}">
                     {% if item.is_available %}В наличии{% else %}Нет в наличии{% endif %}
                 </span>
             </div>
 
-            <div class="product-summary__swatches" aria-hidden="true">
-                <span class="product-summary__swatch product-summary__swatch--dark"></span>
-                <span class="product-summary__swatch product-summary__swatch--graphite"></span>
-                <span class="product-summary__swatch product-summary__swatch--taupe"></span>
-                <span class="product-summary__swatch product-summary__swatch--sand"></span>
-            </div>
+            {% if item.color %}
+                <div class="product-summary__swatches" aria-label="Цвет товара">
+                    <span
+                        class="product-summary__swatch product-summary__swatch--active"
+                        style="background: {{ item.color.hex_code }};"
+                        title="{{ item.color.name }}"
+                    ></span>
+                    <span class="product-summary__color-name">{{ item.color.name }}</span>
+                </div>
+            {% endif %}
 
             {% if item.description %}
                 <div class="product-summary__description">{{ item.description|linebreaksbr }}</div>