Add read receipt tracking for sent mail

Wino.Core.Domain/Entities/Mail/SentMailReceiptState.cs

@@ -0,0 +1,25 @@
+using System;
+using SQLite;
+using Wino.Core.Domain.Enums;
+
+namespace Wino.Core.Domain.Entities.Mail;
+
+public class SentMailReceiptState
+{
+    [PrimaryKey]
+    public Guid MailUniqueId { get; set; }
+
+    public Guid AccountId { get; set; }
+
+    public string MessageId { get; set; }
+
+    public bool IsReceiptRequested { get; set; }
+
+    public DateTime RequestedAtUtc { get; set; }
+
+    public SentMailReceiptStatus Status { get; set; }
+
+    public DateTime? AcknowledgedAtUtc { get; set; }
+
+    public Guid? ReceiptMessageUniqueId { get; set; }
+}