feat(AddReportBehavior): add PDF report generation logic with logging

- Introduced `ILogger<AddReportBehavior>` for logging support.
- Added `DoCreateReport` method to generate PDF from `EnvelopeReport` items.
- Added `ReportSource` class to structure report data.
- Retained existing history creation and MediatR pipeline behavior.

EnvelopeGenerator.Application/Pdf/Behaviors/AddReportBehavior.cs

@@ -4,6 +4,7 @@ using EnvelopeGenerator.Domain.Constants;
 using EnvelopeGenerator.Application.EnvelopeReports;
 using EnvelopeGenerator.Application.Exceptions;
 using EnvelopeGenerator.Domain.Entities;
+using Microsoft.Extensions.Logging;
 
 namespace EnvelopeGenerator.Application.Pdf.Behaviors;
 
@@ -14,13 +15,17 @@ public class AddReportBehavior : IPipelineBehavior<BurnPdfCommand, byte[]>
 {
     private readonly ISender _sender;
 
+    private readonly ILogger<AddReportBehavior> _logger;
+
     /// <summary>
     /// 
     /// </summary>
     /// <param name="sender"></param>
-    public AddReportBehavior(ISender sender)
+    /// <param name="logger"></param>
+    public AddReportBehavior(ISender sender, ILogger<AddReportBehavior> logger)
     {
         _sender = sender;
+        _logger = logger;
     }
 
     /// <summary>
@@ -68,4 +73,35 @@ public class AddReportBehavior : IPipelineBehavior<BurnPdfCommand, byte[]>
 
         return oBuffer;
     }
+
+    private byte[] DoCreateReport(IEnumerable<EnvelopeReport> oItems)
+    {
+        var oSource = new ReportSource { Items = oItems };
+        var oReport = new rptEnvelopeHistory
+        {
+            DataSource = oSource,
+            DataMember = "Items"
+        };
+
+        // Creating report in memory
+        oReport.CreateDocument();
+
+        // Exporting report to stream
+        using var oStream = new MemoryStream();
+        oReport.ExportToPdf(oStream);
+
+        // Writing report to buffer
+        return oStream.ToArray();
+    }
+
+    /// <summary>
+    /// 
+    /// </summary>
+    public class ReportSource
+    {
+        /// <summary>
+        /// 
+        /// </summary>
+        public required IEnumerable<EnvelopeReport> Items { get; init; }
+    }
 }