Add [NotMapped] for Envelope property on .NET Framework

Applied the [NotMapped] attribute to a property in the Envelope class when targeting .NET Framework, ensuring it is not mapped to a database column by Entity Framework in that environment. No changes for other frameworks.

EnvelopeGenerator.Domain/Entities/Envelope.cs

@@ -140,7 +140,9 @@ namespace EnvelopeGenerator.Domain.Entities
             = false;
 #endif
 
+#if NETFRAMEWORK
         [NotMapped]
+#endif
         [Column("DOC_RESULT")]
         public byte[]
 #if nullable