Use already existing images for thumbnails

[Shakahron]

I'm sure this is really edge case, but this is the way I have my library set up for use with Komga. If an image is in the same location, with the exact same file name as an archive, Lanraragi could use that image as the thumbnail instead of generating one or replace already existing thumbnails. This is handy for archives where the title page isn't the first page in the archive.

I don't know how difficult something like this is to implement or maybe it's just too niche but either way I would understand.

[Difegue]

👋 I guess this wouldn't be too hard to do as a thumbnail override - if an image with the same name exists, use that instead.

That'd mean all existing thumbail features would do nothing though, so there's a potential documentation pitfall - tagging this as volunteers for now.