Add CuNNy as a Default Scaling Mode

[MarvNC]

Expected behavior 预期的功能

CuNNy is available as a default scaling mode

Reason: I linked Magpie to a friend and they were confused because they could not find this mode for upscaling. I think it is warranted as CuNNy is the best out of the box upscaler for visual novel art.

Alternative behavior (optional) 近似的功能（可选）

No response

[Blinue]

It's a great idea—CuNNy works better than Anime4K when scaling visual novels. Just keep in mind that changes to the default scaling modes are only visible to new users. If a configuration file already exists, Magpie will read it without making any changes.