cache thumbnails

AobaCore/Models/MediaThumbnail.cs

@@ -0,0 +1,19 @@
+using MongoDB.Bson;
+using MongoDB.Bson.Serialization.Attributes;
+
+namespace AobaCore.Models;
+
+public record MediaThumbnail
+{
+	[BsonId]
+	public required ObjectId Id { get; init; }
+	public Dictionary<ThumbnailSize, ObjectId> Sizes { get; set; } = [];
+}
+
+public enum ThumbnailSize
+{
+	Small = 128,
+	Medium = 256,
+	Large = 512,
+	ExtraLarge = 1024
+}