Implemented image preloading

src/Models/AdminSettingsModel.cs

@@ -11,9 +11,17 @@ public class AdminSettingsModel
     public required string BarcodeText { get; set; }
     public required Dictionary<string, Preset> Presets { get; set; }
     public HashAlgorithm? hashAlgorithm;
+    public UserImagePreloadType? UserImagePreloadType { get; set; } = Models.UserImagePreloadType.None;
 }
 
 public class Preset
 {
     public required Dictionary<string, string> Attribute { get; set; }
+}
+
+public enum UserImagePreloadType
+{
+    None,
+    Icons,
+    FullSized
 }