Refactor DTOs for improved structure and documentation

Transitioned from records to classes for flexibility, added XML documentation for clarity, and updated property definitions to use standard getters and setters. Introduced the `required` keyword for essential properties, removed unnecessary constructors, and enhanced property descriptions for better readability. Additionally, overridden `GetHashCode` in `ReceiverReadDto` for proper collection behavior.

EnvelopeGenerator.Application/DTOs/EnvelopeCertificateDto.cs

@@ -1,16 +1,51 @@
 using DigitalData.Core.Abstractions;
 using Microsoft.AspNetCore.Mvc;
 
-namespace EnvelopeGenerator.Application.DTOs
+namespace EnvelopeGenerator.Application.DTOs;
+
+/// <summary>
+/// Data Transfer Object representing certificate information for an envelope.
+/// </summary>
+[ApiExplorerSettings(IgnoreApi = true)]
+public class EnvelopeCertificateDto : IUnique<int>
 {
-    [ApiExplorerSettings(IgnoreApi = true)]
-    public record EnvelopeCertificateDto(
-        int Id,
-        int EnvelopeId,
-        string EnvelopeUuid,
-        string EnvelopeSubject,
-        int CreatorId,
-        string CreatorName,
-        string CreatorEmail,
-        int EnvelopeStatus) : IUnique<int>;
+    /// <summary>
+    /// Gets the unique identifier of the certificate.
+    /// </summary>
+    public int Id { get; init; }
+
+    /// <summary>
+    /// Gets the envelope ID associated with the certificate.
+    /// </summary>
+    public int EnvelopeId { get; init; }
+
+    /// <summary>
+    /// Gets the UUID of the envelope.
+    /// </summary>
+    public string EnvelopeUuid { get; init; }
+
+    /// <summary>
+    /// Gets the subject of the envelope.
+    /// </summary>
+    public string EnvelopeSubject { get; init; }
+
+    /// <summary>
+    /// Gets the ID of the creator of the envelope.
+    /// </summary>
+    public int CreatorId { get; init; }
+
+    /// <summary>
+    /// Gets the name of the creator.
+    /// </summary>
+    public string CreatorName { get; init; }
+
+    /// <summary>
+    /// Gets the email address of the creator.
+    /// </summary>
+    public string CreatorEmail { get; init; }
+
+    /// <summary>
+    /// Gets the current status of the envelope.
+    /// </summary>
+    public int EnvelopeStatus { get; init; }
 }