implement media serving

AobaCore/AobaService.cs

@@ -9,7 +9,6 @@ public class AobaService(IMongoDatabase db)
 {
 	private readonly IMongoCollection<Media> _media = db.GetCollection<Media>("media");
 
-
 	public async Task<Media?> GetMediaAsync(ObjectId id)
 	{
 		return await _media.Find(m => m.Id == id).FirstOrDefaultAsync();
@@ -19,4 +18,9 @@ public class AobaService(IMongoDatabase db)
 	{
 		return _media.InsertOneAsync(media);
 	}
+	
+	public Task IncrementViewCountAsync(ObjectId id)
+	{
+		return _media.UpdateOneAsync(m => m.Id == id, Builders<Media>.Update.Inc(m => m.ViewCount, 1));
+	}
 }