blairtcg/sumi ? reverse-engineered prompt

Build me the Sumi service that renders card drop images for Blair.

I want a small local service that runs on port 8888 by default, takes in card image requests, caches generated card data in memory, reads card assets from disk when needed, and returns the finished image bytes back to the main app. It should be able to decode and encode webp images, draw text and layout onto a canvas, and reuse cached cards when possible so repeated requests are fast.

Please make it easy to run with a simple start command, and include a build command and a way to stop or list running renderer processes too. If there are any missing details, check the existing README and look up current docs online if you need to. Keep it clean, fast, and ready to run locally, with sensible defaults and clear logging.