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

src/app/core/services/checkout.service.ts

@@ -3,7 +3,14 @@ import { HttpClient } from '@angular/common/http';
 import { firstValueFrom } from 'rxjs';
 
 import { environment } from '../../../environments/environment';
-import { BankAccount } from './tenant.interface';
+
+export interface CreatePurchasePayload {
+  cart_id: number;
+  dni: string;
+  telefono: string;
+  nombre_apellido: string;
+  email: string;
+}
 
 @Injectable({
   providedIn: 'root'
@@ -11,7 +18,7 @@ import { BankAccount } from './tenant.interface';
 export class CheckoutService {
   private readonly http = inject(HttpClient);
 
-  async createPurchase(tenantCode: string, payload: any): Promise<{ id: number }> {
+  async createPurchase(tenantCode: string, payload: CreatePurchasePayload): Promise<{ id: number }> {
     const response = await firstValueFrom(
       this.http.post<{ data: { id: number } }>(`${environment.url}tenants/${tenantCode}/compras`, payload)
     );