Make References required in InsertResultCommand

Changed the References property in InsertResultCommand from a nullable type to required. References must now always be provided and cannot be null when creating an InsertResultCommand instance. This enforces stricter data integrity for command creation.

src/ReC.Application/Results/Commands/InsertResultCommand.cs

@@ -15,7 +15,7 @@ public record InsertResultCommand : IInsertProcedure
     public string? InfoDetail { get; set; }
     public string? Error { get; set; }
     public required ResultType Type { get; set; }
-    public InvokeReferences? References { get; set; }
+    public required InvokeReferences References { get; set; }
 }
 
 public class InsertResultProcedureHandler(ISender sender) : IRequestHandler<InsertResultCommand, long>