doesn't really need to be two seperate libraries. also preperation for other funnies the build script has been replaced with a much saner justfile which uses much saner "yarn workspace" invocations instead of blindly cding all over the place
This module also does threadpooling internally, so we don't need Piscina anymore (which I'm pretty sure was actually bottlenecking.)
Additionally make thumbnail encoding threadpooled as well, just so it (probably) doesn't block as much.
