Koreader progress sync interface (#3025)

Co-authored-by: Joe Milazzo <josephmajora@gmail.com>

API/Entities/MangaFile.cs

@@ -1,4 +1,4 @@
-
+
 using System;
 using System.IO;
 using API.Entities.Enums;
@@ -21,6 +21,11 @@ public class MangaFile : IEntityDate
     /// </summary>
     public required string FilePath { get; set; }
     /// <summary>
+    /// A hash of the document using Koreader's unique hashing algorithm
+    /// <remark> KoreaderHash is only available for epub types </remark>
+    /// </summary>
+    public string? KoreaderHash { get; set; }
+    /// <summary>
     /// Number of pages for the given file
     /// </summary>
     public int Pages { get; set; }