Introduced `ESignParams` for configurable e-signature settings,
including `ApplicationName` and `DefaultReason`. Updated
`DocReceiverElementDto` and `PdfSignOptionsDto` to support
new properties. Registered `ESignParams` in DI container.
Refactored `SignPdfByElementCommand` to include new fields
and improved error handling. Added `SignPdfByEnvelopeReceiverCommand`
to enable signing documents for envelope receivers.
Replaced DevExpress with PdfSharp for PDF rendering in
`ReceiverSignedPage.razor`, improving layout and flexibility.
Enhanced `PdfSignatureController` with a new endpoint for
signing documents by envelope key.
Added `DataIntegrityException` for better error handling.
Updated `appsettings.json` with `ESignParams` configuration.
Introduced `ReadEnvelopeReceiverSecretQuery` to fetch sensitive
fields (e.g., access code, phone number) for envelope receivers.
Added extension methods for dispatching the query via `IMediator`
and implemented `ReadEnvelopeReceiverSecretQueryHandler` to
process the query using repositories and AutoMapper.
Updated `EnvelopeController` with a new HTTP GET endpoint
`EnvelopeReceiverWithSecretByMediatr` to expose the query
functionality. This endpoint returns sensitive data as
`EnvelopeReceiverSecretDto` or a 404 response if no match is found.
These changes improve modularity, testability, and separation of
concerns by leveraging MediatR and CQRS patterns.
