feat(discount): add InStock filter to discount product queries and mappings

- Introduced InStock property to GetDiscountProductsQuery and GetCustomerProductsByFilterQuery for filtering based on product availability.
- Updated query handlers to apply InStock filtering logic in both discount and customer product queries.
- Enhanced mapping configurations to include InStock in the response DTOs.
- Bumped Protobuf project version to reflect the addition of new features.

src/CMSMicroservice.WebApi/Services/ProductsService.cs

@@ -175,6 +175,7 @@ public class ProductsService : ProductsContract.ProductsContractBase
             SaleCount = request.Filter?.SaleCount,
             ViewCount = request.Filter?.ViewCount,
             RemainingCount = request.Filter?.RemainingCount,
+            InStock = request.Filter?.InStock,
             CategoryIds = request.Filter?.CategoryId.HasValue == true 
                 ? new List<long> { request.Filter.CategoryId.Value } 
                 : new List<long>(),
@@ -567,6 +568,7 @@ public class ProductsService : ProductsContract.ProductsContractBase
             SaleCount = request.Filter?.SaleCount,
             ViewCount = request.Filter?.ViewCount,
             RemainingCount = request.Filter?.RemainingCount,
+            InStock = request.Filter?.InStock,
             CategoryIds = request.Filter?.CategoryId != null ? new List<long> { request.Filter.CategoryId.Value } : null
         };