feat: add product variant management functionality

- Implemented CreateProductVariantDto and UpdateProductVariantDto for product variant data transfer.
- Developed ProductVariantsController to handle CRUD operations for product variants.
- Created ProductVariantsService to interact with the database using Prisma.
- Added ProductVariantsModule to encapsulate the product variant feature.
- Included response mapping for consistent API responses.

src/app.module.ts

@@ -6,7 +6,7 @@ import { InventoriesModule } from './inventories/inventories.module'
 import { PrismaModule } from './prisma/prisma.module'
 import { ProductBrandsModule } from './product-brands/product-brands.module'
 import { ProductCategoriesModule } from './product-categories/product-categories.module'
-import { ProductInfoModule } from './product-info/product-info.module'
+import { ProductVariantsModule } from './product-variants/product-variants.module'
 import { ProductsModule } from './products/products.module'
 import { RolesModule } from './roles/roles.module'
 import { StoresModule } from './stores/stores.module'
@@ -19,7 +19,7 @@ import { UsersModule } from './users/users.module'
     UsersModule,
     RolesModule,
     ProductsModule,
-    ProductInfoModule,
+    ProductVariantsModule,
     ProductBrandsModule,
     ProductCategoriesModule,
     SuppliersModule,