A new `SenderAppType` enum was introduced in the
`EnvelopeGenerator.ReceiverUI.Models.Constants` namespace, with
values `LegacyFormApp` and `ReceiverUIBlazorApp`.
The `SignatureDto` class was updated to include a new property of
type `SenderAppType`, enabling the specification of the sender
application type for a signature.
Additionally, a `using` directive for the
`EnvelopeGenerator.ReceiverUI.Models.Constants` namespace was added
to `SignatureDto.cs` to support the use of the new enum.