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

items/migrations/0004_color_item_discount_price_item_is_new_item_color.py

@@ -0,0 +1,42 @@
+# Generated by Django 6.0.5 on 2026-05-25 15:20
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('items', '0003_subcategory_item_subcategory_and_more'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Color',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('name', models.CharField(max_length=100, verbose_name='Название цвета')),
+                ('hex_code', models.CharField(help_text='Например, #FF5500', max_length=7, verbose_name='Цвет (HEX)')),
+            ],
+            options={
+                'verbose_name': 'Цвет',
+                'verbose_name_plural': 'Цвета',
+                'ordering': ('name',),
+            },
+        ),
+        migrations.AddField(
+            model_name='item',
+            name='discount_price',
+            field=models.DecimalField(blank=True, decimal_places=2, max_digits=10, null=True, verbose_name='Цена со скидкой'),
+        ),
+        migrations.AddField(
+            model_name='item',
+            name='is_new',
+            field=models.BooleanField(default=False, verbose_name='Новинка'),
+        ),
+        migrations.AddField(
+            model_name='item',
+            name='color',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='items', to='items.color', verbose_name='Цвет'),
+        ),
+    ]