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

static/css/catalog.css

@@ -298,6 +298,12 @@ aside {
     margin-top: 18px;
 }
 
+.item-card-price-block {
+    display: flex;
+    flex-direction: column;
+    gap: 2px;
+}
+
 .item-card-price {
     color: #36213e;
     font-weight: 700;
@@ -305,6 +311,18 @@ aside {
     line-height: 1.2;
 }
 
+.item-card-price--discount {
+    color: #c54c5d;
+}
+
+.item-card-price-original {
+    color: #8a8a9a;
+    font-size: 15px;
+    font-weight: 400;
+    text-decoration: line-through;
+    line-height: 1.2;
+}
+
 .item-card-availability {
     flex: 0 0 auto;
     color: #554971;
@@ -411,12 +429,18 @@ aside {
 
 .product-summary__meta {
     display: flex;
-    align-items: baseline;
+    align-items: center;
     flex-wrap: wrap;
     gap: 18px;
     margin-top: 16px;
 }
 
+.product-summary__price-block {
+    display: flex;
+    flex-direction: column;
+    gap: 2px;
+}
+
 .product-summary__price {
     color: #36213e;
     font-weight: 700;
@@ -424,6 +448,23 @@ aside {
     line-height: 1.2;
 }
 
+.product-summary__price--discount {
+    color: #c54c5d;
+}
+
+.product-summary__price-original {
+    color: #8a8a9a;
+    font-size: 18px;
+    font-weight: 400;
+    text-decoration: line-through;
+    line-height: 1.2;
+}
+
+.product-summary__color-name {
+    font-size: 16px;
+    color: #554971;
+}
+
 .product-summary__availability {
     color: #554971;
     font-size: 17px;
@@ -452,20 +493,8 @@ aside {
     display: block;
 }
 
-.product-summary__swatch--dark {
-    background: #303438;
-}
-
-.product-summary__swatch--graphite {
-    background: #5f6767;
-}
-
-.product-summary__swatch--taupe {
-    background: #927d68;
-}
-
-.product-summary__swatch--sand {
-    background: #cfc3ae;
+.product-summary__swatch--active {
+    box-shadow: 0 0 0 2px #ffffff, 0 0 0 4px #554971;
 }
 
 .product-summary__description {
@@ -606,3 +635,83 @@ aside {
         width: 100%;
     }
 }
+
+/* Sidebar section links (Акции / Новинки headings) */
+.sidebar-section-link {
+    color: inherit;
+    text-decoration: none;
+    transition: color 0.2s;
+}
+
+.sidebar-section-link:hover,
+.sidebar-section-link.active {
+    color: #36213e;
+    text-decoration: underline;
+}
+
+/* Sidebar mini-cards */
+.sidebar-mini-card {
+    display: flex;
+    gap: 10px;
+    align-items: flex-start;
+    margin-bottom: 12px;
+}
+
+.sidebar-mini-card__img-link {
+    flex: 0 0 52px;
+    width: 52px;
+    height: 52px;
+    display: block;
+    overflow: hidden;
+    background: rgba(99, 118, 141, 0.1);
+    border-radius: 4px;
+}
+
+.sidebar-mini-card__img-link img {
+    width: 100%;
+    height: 100%;
+    object-fit: cover;
+    display: block;
+}
+
+.sidebar-mini-card__body {
+    min-width: 0;
+    display: flex;
+    flex-direction: column;
+    gap: 4px;
+}
+
+.sidebar-mini-card__name {
+    color: #36213e;
+    font-size: 15px;
+    line-height: 1.2;
+    display: -webkit-box;
+    -webkit-line-clamp: 2;
+    -webkit-box-orient: vertical;
+    overflow: hidden;
+    text-decoration: none;
+    transition: text-decoration-color 0.2s;
+}
+
+.sidebar-mini-card__name:hover {
+    text-decoration: underline;
+}
+
+.sidebar-mini-card__price {
+    color: #554971;
+    font-size: 14px;
+    font-weight: 600;
+}
+
+.sidebar-more-link {
+    display: inline-block;
+    margin-top: 4px;
+    color: #63768d;
+    font-size: 15px;
+    text-decoration: underline;
+    transition: color 0.2s;
+}
+
+.sidebar-more-link:hover {
+    color: #36213e;
+}