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.

prisma/schema/enum.prisma

@@ -1,5 +1,7 @@
 enum PaymentMethodType {
+  TERMINAL
   CASH
+  SET_OFF
   CARD
   BANK
   CHECK
@@ -25,3 +27,14 @@ enum UnitType {
   METER
   HOUR
 }
+
+enum CustomerType {
+  INDIVIDUAL
+  LEGAL
+  UNKNOWN
+}
+
+enum SalesInvoiceItemPricingModel {
+  STANDARD
+  GOLD
+}