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/account/models.py

@@ -61,6 +61,15 @@ class User(AbstractBaseUser, PermissionsMixin):
     # def groups(self):
     #     return None
 
+
+    def generate_special_code(self):
+        """Generate and save a unique special code for the user if missing."""
+        # simple deterministic code based on phone and timestamp hash
+        base = f"{self.phone}-{timezone.now().timestamp()}"
+        code = hashlib.sha256(base.encode()).hexdigest()[:12].upper()
+
+        return code
+
     @property
     def full_name(self):
         if self.first_name and self.last_name:
@@ -120,6 +129,14 @@ class User(AbstractBaseUser, PermissionsMixin):
             return self.phone
 
 
+class SpecialDiscountCode(models.Model):
+    user = models.OneToOneField(User, on_delete=models.PROTECT, related_name='spital_code')
+    code = models.CharField(max_length=12, unique=True)
+
+    def __str__(self):
+        return f'{self.user} - {self.code}'
+
+
 
 class ShopModel(models.Model):
     user = models.OneToOneField(User, on_delete=models.CASCADE, related_name='shop', verbose_name='کاربر')