feat: implement POS order management system

- Added CreateOrderDto and CreateOrderItemDto for order creation.
- Developed PosOrdersController to handle order-related endpoints.
- Created PosOrdersService for business logic related to orders.
- Implemented PosOrdersWorkflow for order processing workflows.
- Established Prisma integration for database operations in orders.
- Introduced SalesInvoicesModule and related DTOs for sales invoice management.
- Enhanced SalesInvoicesService and SalesInvoicesWorkflow for invoice processing.

prisma/schema/inventory.prisma

@@ -47,6 +47,7 @@ model PosAccount {
 
   inventoryBankAccount InventoryBankAccount @relation(fields: [inventoryId, bankAccountId], references: [inventoryId, bankAccountId])
   salesInvoices        SalesInvoice[]
+  orders               Order[]
 
   @@index([inventoryId])
   @@map("Pos_Accounts")