Refactor DocumentDto to use DocumentDetailsDto

Introduce a new `DocumentDetailsDto` record to encapsulate shared document metadata and elements without binary payload. Refactor `DocumentDto` to inherit from `DocumentDetailsDto`, eliminating redundant properties and improving code reuse.

Convert `DocumentDto` from a class to a record for immutability. Add a parameterized constructor to `DocumentDto` for initializing binary data alongside metadata. Update `ByteData` to use the `init` accessor.

These changes enhance maintainability, reduce duplication, and enforce immutability by leveraging C# records and inheritance.

EnvelopeGenerator.Application/Common/Dto/DocumentDetailsDto.cs

@@ -0,0 +1,27 @@
+namespace EnvelopeGenerator.Application.Common.Dto;
+
+/// <summary>
+/// Data Transfer Object representing document metadata and elements without binary payload.
+/// </summary>
+public record DocumentDetailsDto
+{
+    /// <summary>
+    /// Gets or sets the unique identifier of the document.
+    /// </summary>
+    public int Id { get; init; }
+
+    /// <summary>
+    /// Gets or sets the envelope ID to which the document belongs.
+    /// </summary>
+    public int EnvelopeId { get; init; }
+
+    /// <summary>
+    /// Gets or sets the date and time when the document was added.
+    /// </summary>
+    public DateTime AddedWhen { get; init; }
+
+    /// <summary>
+    /// Gets or sets the collection of elements associated with the document for receiver interactions, if any.
+    /// </summary>
+    public IEnumerable<DocReceiverElementDto>? Elements { get; init; }
+}

EnvelopeGenerator.Application/Common/Dto/DocumentDto.cs

@@ -3,30 +3,25 @@
 /// <summary>
 /// Data Transfer Object representing a document within an envelope, including optional binary data and form elements.
 /// </summary>
-public class DocumentDto
+public record DocumentDto : DocumentDetailsDto
 {
     /// <summary>
-    /// Gets or sets the unique identifier of the document.
+    /// 
     /// </summary>
-    public int Id { get; set; }
+    public DocumentDto() { }
 
     /// <summary>
-    /// Gets or sets the envelope ID to which the document belongs.
+    /// 
     /// </summary>
-    public int EnvelopeId { get; set; }
+    /// <param name="byteData"></param>
-
+    /// <param name="details"></param>
-    /// <summary>
+    public DocumentDto(byte[] byteData, DocumentDetailsDto details) : base(details)
-    /// Gets or sets the date and time when the document was added.
+    {
-    /// </summary>
+        ByteData = byteData;
-    public DateTime AddedWhen { get; set; }
+    }
 
     /// <summary>
     /// Gets or sets the binary data of the document, if available.
     /// </summary>
-    public byte[]? ByteData { get; set; }
+    public byte[]? ByteData { get; init; }
-
+}
-    /// <summary>
-    /// Gets or sets the collection of elements associated with the document for receiver interactions, if any.
-    /// </summary>
-    public IEnumerable<DocReceiverElementDto>? Elements { get; set; }
-}