Added a UTC timestamp for reading history events (#3640)

API/DTOs/Statistics/ReadHistoryEvent.cs

@@ -13,6 +13,7 @@ public class ReadHistoryEvent
     public int SeriesId { get; set; }
     public required string SeriesName { get; set; } = default!;
     public DateTime ReadDate { get; set; }
+    public DateTime ReadDateUtc { get; set; }
     public int ChapterId { get; set; }
     public required float ChapterNumber { get; set; } = default!;
 }

API/Services/StatisticService.cs

@@ -357,6 +357,7 @@ public class StatisticService : IStatisticService
                 SeriesId = u.SeriesId,
                 LibraryId = u.LibraryId,
                 ReadDate = u.LastModified,
+                ReadDateUtc = u.LastModifiedUtc,
                 ChapterId = u.ChapterId,
                 ChapterNumber = _context.Chapter.Single(c => c.Id == u.ChapterId).MinNumber
             })