refactor(BurnPdfCommand): add Report property to forward report.

- Reverse the order in which behaviors are added.

EnvelopeGenerator.Application/DependencyInjection.cs

@@ -87,11 +87,13 @@ public static class DependencyInjection
         services.AddMediatR(cfg =>
         {
             cfg.RegisterServicesFromAssembly(Assembly.GetExecutingAssembly());
+
+            cfg.AddBehavior<CreateHistoryBehavior>();
+            cfg.AddBehavior<SavePdfBehavior>();
 #if WINDOWS
+            cfg.AddBehavior<PdfMergeBehavior>();
             cfg.AddBehavior<AddReportBehavior>();
 #endif
-            cfg.AddBehavior<SavePdfBehavior>();
-            cfg.AddBehavior<CreateHistoryBehavior>();
         });
 
         // Add memory cache