feat(checkout): define CreatePurchasePayload interface and update createPurchase method to use it

src/app/features/store/pages/checkout-page/checkout-page.component.ts

@@ -5,7 +5,7 @@ import { startWith } from 'rxjs';
 
 import { CartService } from '../../../../core/services/cart/cart.service';
 import { TenantService } from '../../../../core/services/tenant.service';
-import { CheckoutService } from '../../../../core/services/checkout.service';
+import { CheckoutService, CreatePurchasePayload } from '../../../../core/services/checkout.service';
 import { BankAccount } from '../../../../core/services/tenant.interface';
 import { CartItem } from '../../../../core/services/cart/cart.interface';
 import { CartComponent, CartItemMock } from '../../../../shared/components/cart/cart.component';
@@ -125,15 +125,18 @@ export class CheckoutPageComponent {
     this.isCreatingPurchase.set(true);
 
     try {
-      const cartItems = this.cartService.cart()?.items || [];
+      const cart = this.cartService.cart();
+      if (!cart?.id) {
+        throw new Error('No hay un carrito activo para finalizar la compra.');
+      }
+
       const formValue = this.form.getRawValue();
-      const payload = {
-        ...formValue,
+      const payload: CreatePurchasePayload = {
+        cart_id: cart.id,
+        dni: formValue.dni,
+        telefono: formValue.telefono,
+        email: formValue.email,
         nombre_apellido: formValue.nombre,
-        items: cartItems.map((item) => ({
-          producto_variante_id: item.product_variant_id,
-          cantidad: item.cantidad
-        }))
       };
 
       const response = await this.checkoutService.createPurchase(tenant.codigo, payload);