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/stores/dto/update-store.dto.ts

@@ -1,5 +1,17 @@
+import { Type } from 'class-transformer'
+import { IsBoolean, IsOptional, IsString } from 'class-validator'
+
 export class UpdateStoreDto {
+  @IsOptional()
+  @IsString()
   name?: string
+
+  @IsOptional()
+  @IsString()
   location?: string
+
+  @IsOptional()
+  @Type(() => Boolean)
+  @IsBoolean()
   isActive?: boolean
 }