Set Message default via ctor for .NET Framework only

Removed default value assignment from Message property and added a constructor to set the default message only when compiling for .NET Framework, using conditional compilation. This improves cross-platform compatibility.

EnvelopeGenerator.Domain/Entities/Envelope.cs

@@ -14,6 +14,13 @@ namespace EnvelopeGenerator.Domain.Entities
     [Table("TBSIG_ENVELOPE", Schema = "dbo")]
     public class Envelope
     {
+        public Envelope()
+        {
+#if NETFRAMEWORK
+            Message = My.Resources.Envelope.Please_read_and_sign_this_document;
+#endif
+        }
+
         // TODO: * Check the Form App and remove the default value
         [Key]
         [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
@@ -39,7 +46,7 @@ namespace EnvelopeGenerator.Domain.Entities
 
         // TODO: * Check the Form App and remove the default value
         [Column("MESSAGE", TypeName = "nvarchar(max)")]
-        public string Message { get; set; } = My.Resources.Envelope.Please_read_and_sign_this_document;
+        public string Message { get; set; }
 
         [Column("EXPIRES_WHEN", TypeName = "datetime")]
         public DateTime ExpiresWhen { get; set; }