Fixed a bug in ScanLibrary that caused duplicated Volumes. Implemented APIs for navigating down to Volume for webui.

This is rough code and needs to be polished and refactored.

API/DTOs/LibraryDto.cs

@@ -5,6 +5,7 @@ namespace API.DTOs
 {
     public class LibraryDto
     {
+        public int Id { get; init; }
         public string Name { get; set; }
         public string CoverImage { get; set; }
         public LibraryType Type { get; set; }