4e84a15db7
- Added INumberSequenceService interface for generating document numbers. - Created NumberSequenceService to handle atomic document number issuance. - Introduced IPurchaseOrderService interface and implemented PurchaseOrderService for managing purchase orders. - Added IRequisitionService interface and implemented RequisitionService for handling requisitions. - Created IRfqService interface and implemented RfqService for managing RFQs and vendor quotations. - Defined necessary DTOs and domain entities for procurement processes. - Ensured proper validation and error handling across services.