Add e-signature support and improve PDF signing process

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.

EnvelopeGenerator.Application/PdfSigning/SignPdfByElementCommand.cs

@@ -1,9 +1,12 @@
 using DigitalData.Core.Exceptions;
+using EnvelopeGenerator.Application.Common.Configurations;
 using EnvelopeGenerator.Application.Common.Dto;
+using EnvelopeGenerator.Application.Common.Enums;
 using EnvelopeGenerator.Application.Common.Interfaces.Doc;
 using EnvelopeGenerator.Application.Common.Interfaces.Services;
 using EnvelopeGenerator.Application.DocReceiverElements.Queries;
 using MediatR;
+using Microsoft.Extensions.Options;
 
 namespace EnvelopeGenerator.Application.PdfSigning;
 
@@ -21,13 +24,36 @@ public record SignPdfByElementCommand : IRequest<Stream>
     /// 
     /// </summary>
     public int? ElementId { get; init; }
+
+    /// <summary>
+    /// Custom document 
+    /// </summary>
+    public Stream? Document { get; set; }
+
+    /// <summary>
+    /// 
+    /// </summary>
+    public string? Phone { get; set; }
+
+    /// <summary>
+    /// 
+    /// </summary>
+    public string? Reason { get; set; }
+
+    /// <summary>
+    /// 
+    /// </summary>
+    public PdfSignatureCertificationLevel CertificationLevel { get; init; } = PdfSignatureCertificationLevel.NoChangesAllowed;
 }
 
 /// <summary>
 /// 
 /// </summary>
+/// <param name="sender"></param>
 /// <param name="signService"></param>
-public class SignPdfCommandHandler(ISender sender, IPdfDigitalSignatureService signService, IPdfPageImageRenderer imgRenderer) : IRequestHandler<SignPdfByElementCommand, Stream>
+/// <param name="imgRenderer"></param>
+/// <param name="options"></param>
+public class SignPdfCommandHandler(ISender sender, IPdfDigitalSignatureService signService, IPdfPageImageRenderer imgRenderer, IOptionsMonitor<ESignParams> options) : IRequestHandler<SignPdfByElementCommand, Stream>
 {
     /// <summary>
     /// 
@@ -37,49 +63,71 @@ public class SignPdfCommandHandler(ISender sender, IPdfDigitalSignatureService s
     /// <returns></returns>
     public async Task<Stream> Handle(SignPdfByElementCommand request, CancellationToken cancellationToken)
     {
+        cancellationToken.ThrowIfCancellationRequested();
+
         // ensure element
-        if(request.Element is null)
+        if (request.Element is null)
         {
             var elements = await sender.Send(new ReadDocReceiverElementQuery() 
             {
                 Id = request.ElementId!,
-                IncludeDocument= true
+                IncludeDocument = request.Document is null
             }, cancellationToken);
             
-            if (!elements.Any())
-                throw new NotFoundException($"Element with ID {request.ElementId} not found.");
-
-            request.Element = elements.FirstOrDefault();
+            request.Element = elements.FirstOrDefault() ?? throw new NotFoundException($"Element with ID {request.ElementId} not found."); ;
         }
 
         // ensure document
-        var doc = request.Element!.Document;
+        if(request.Document is null)
+        {
+            if (request.Element?.Document?.ByteData is not { Length: > 0 })
+                throw new NotFoundException("Document data is missing or empty.");
 
-        if(doc is null || doc.ByteData is null || doc.ByteData.Length == 0)
-            throw new NotFoundException("Document data is missing or empty.");
+            request.Document = new MemoryStream(request.Element.Document.ByteData);
+        }
+
+        ValidateAfterDataIsComplete(request);
 
         // create signature image from element
         var img = imgRenderer.ComposeSignaturePreviewPng(request.Element);
 
         // sign pdf
-        var inputPdf = new MemoryStream(doc.ByteData);
         var outputPdf = new MemoryStream();
 
         await signService.SignPdfAsync(
-            inputPdf: inputPdf,
+            inputPdf: request.Document,
             outputPdf: outputPdf,
             options: new PdfSignOptionsDto
             {
+                Name = request.Element.FullName!,
+                Location = request.Element.Position!,
+                Phone = request.Phone,
+                Reason = request.Reason ?? options.CurrentValue.DefaultReason,
+                Email = request.Element.Receiver!.EmailAddress,
+                ApplicationName = options.CurrentValue.ApplicationName,
+                DocumentElementId = request.Element.Id,
+
+                CertificationLevel = request.CertificationLevel,
                 Appearance = new PdfSignatureAppearanceDto(
                     PageNumber: request.Element.Page,
                     Left: request.Element.Left,
                     Bottom: request.Element.Y,
                     Width: request.Element.Width,
-                    Height: request.Element.Height)
+                    Height: request.Element.Height,
+                    CoordinateUnit: PdfSignatureCoordinateUnit.Inch,
+                    CoordinateOrigin: PdfSignatureCoordinateOrigin.TopLeft)
             },
             image: img,
             cancellationToken: cancellationToken);
 
         return outputPdf;
     }
+
+    private static void ValidateAfterDataIsComplete(SignPdfByElementCommand request)
+    {
+        if(request.Element!.FullName is null)
+            throw new BadRequestException($"Document is not signed. FullName is required. Element ID: {request.Element.Id}");
+        else if(request.Element.Position is null)
+            throw new BadRequestException($"Document is not signed. Position is required. Element ID: {request.Element.Id}");
+    }
 }