feat(customers): add DTOs for individual and legal customer creation

- Created CreateCustomerIndividualDto for individual customer data with fields: first_name, last_name, national_code, postal_code, is_favorite, and economic_code.
- Created CreateCustomerLegalDto for legal customer data with fields: company_name, economic_code, registration_number, and postal_code.

src/common/interfaces/sale-invoice-payload.ts

@@ -1,7 +1,8 @@
 import { GoldKarat } from '../enums/enums'
 
-export interface SaleInvoicePayload {
-  karat?: keyof typeof GoldKarat
-  wages?: number
-  profit?: number
+export interface SaleInvoiceGoldTypePayload {
+  karat: keyof typeof GoldKarat
+  wages: number
+  profit: number
 }
+export interface SaleInvoiceStandardPayload {}