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/order.prisma

@@ -1,16 +1,22 @@
 model Order {
-  id          Int         @id @default(autoincrement())
-  orderNumber String      @unique @db.VarChar(100)
-  status      OrderStatus @default(PENDING)
-  totalAmount Decimal     @db.Decimal(15, 2)
-  description String?     @db.Text
-  createdAt   DateTime    @default(now()) @db.Timestamp(0)
-  updatedAt   DateTime    @updatedAt @db.Timestamp(0)
-  deletedAt   DateTime?   @db.Timestamp(0)
-  customerId  Int?
-  customer    Customer?   @relation(fields: [customerId], references: [id], onUpdate: NoAction)
-  orderItems  OrderItem[]
+  id           Int         @id @default(autoincrement())
+  orderNumber  String      @unique @db.VarChar(100)
+  status       OrderStatus @default(PENDING)
+  totalAmount  Decimal     @db.Decimal(15, 2)
+  description  String?     @db.Text
+  createdAt    DateTime    @default(now()) @db.Timestamp(0)
+  updatedAt    DateTime    @updatedAt @db.Timestamp(0)
+  deletedAt    DateTime?   @db.Timestamp(0)
+  customerId   Int?
+  posAccountId Int
 
+  customer   Customer?  @relation(fields: [customerId], references: [id], onUpdate: NoAction)
+  posAccount PosAccount @relation(fields: [posAccountId], references: [id], onUpdate: NoAction)
+
+  orderItems        OrderItem[]
+  stockReservations StockReservation[]
+
+  @@index([posAccountId])
   @@index([customerId])
   @@map("Orders")
 }