Use UTC for AddedWhen timestamp in CreateHistoryCommand

Changed AddedWhen to use DateTime.UtcNow instead of DateTime.Now
to ensure timestamps are stored in UTC, improving consistency
across different time zones and deployment environments.

EnvelopeGenerator.Application/Histories/Commands/CreateHistoryCommand.cs

@@ -34,7 +34,7 @@ public record CreateHistoryCommand : EnvelopeReceiverQueryBase, IRequest<History
     /// <summary>
     /// 
     /// </summary>
-    public DateTime AddedWhen { get; } = DateTime.Now;
+    public DateTime AddedWhen { get; } = DateTime.UtcNow;
 
     /// <summary>
     ///