feat: add profit and special discount fields to ProductVariant model

- Updated ProductVariant model to include 'profit' and 'special_discount_percent' fields.
- Added corresponding fields in the admin interface for ProductVariant.
- Created migration to add new fields to the database.

feat: implement special discount code functionality in cart

- Added composables for submitting and deleting special discount codes.
- Updated CartSummary and CartItem components to handle special discount codes.
- Enhanced API endpoints to support special discount operations.
- Updated global types to include special discount code details in the cart.

backend/order/migrations/0038_cart_special_discount_code_and_more.py

@@ -0,0 +1,35 @@
+# Generated by Django 5.1.2 on 2025-11-14 14:07
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('account', '0032_specialdiscountcode'),
+        ('order', '0037_ordermodel_is_stock_rolled_back'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='cart',
+            name='special_discount_code',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.PROTECT, to='account.specialdiscountcode', verbose_name='کدتخفیف خاص'),
+        ),
+        migrations.AddField(
+            model_name='cartitem',
+            name='special_discount_amount',
+            field=models.BigIntegerField(default=0, help_text='تخفیف محاسبه شده از سود تنوع', verbose_name='مقدار تخفیف ویژه'),
+        ),
+        migrations.AddField(
+            model_name='orderitemmodel',
+            name='special_discount_amount',
+            field=models.BigIntegerField(default=0, verbose_name='مقدار تخفیف ویژه'),
+        ),
+        migrations.AddField(
+            model_name='ordermodel',
+            name='special_discount_total',
+            field=models.BigIntegerField(blank=True, null=True, verbose_name='مجموع تخفیف ویژه'),
+        ),
+    ]

backend/order/migrations/0039_remove_cartitem_special_discount_amount.py

@@ -0,0 +1,17 @@
+# Generated by Django 5.1.2 on 2025-11-14 15:19
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('order', '0038_cart_special_discount_code_and_more'),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name='cartitem',
+            name='special_discount_amount',
+        ),
+    ]