BlueSky Image URL Fullsizer από Kin

Replaces feed_thumbnail with feed_fullsize in the url of images.

Amateur copy-paste code, with minor tweaking and stitching. No idea what I'm doing, but seems to work fine. I didn't see anything like Twitter Origifier for Bluesky, so put together this. The permisson is set to "https://cdn.bsky.app/img/*"