feat: add salePrice field to Product model and update related files

- Added salePrice field to Product model in Prisma schema and generated files.
- Updated Product scalar field enums in both TypeScript files.
- Modified aggregate output types to include salePrice.
- Enhanced input types for creating and updating products to support salePrice.
- Updated migration file to add salePrice column to Products table.
- Created DTOs for inventory management in POS module.
- Implemented POS controller and service with methods for stock and product categories.

src/generated/prisma/internal/prismaNamespace.ts

@@ -2068,6 +2068,7 @@ export const ProductScalarFieldEnum = {
   createdAt: 'createdAt',
   updatedAt: 'updatedAt',
   deletedAt: 'deletedAt',
+  salePrice: 'salePrice',
   brandId: 'brandId',
   categoryId: 'categoryId'
 } as const