twentyhq/favicon ? reverse-engineered prompt

Build me a simple open source favicon service that lets me get a company logo just by using its domain name. I want to be able to visit something like /airbnb.com or /github.com/128 and get back the best matching icon, with an optional size, and if no size is given it should use the largest available one. It should support the common favicon sizes and work fast and securely, since this will be used in real products like signup flows or CRM style company pages.

Please make it easy to run locally, with a health check endpoint, and store icons either on the local machine for development or in S3 for production. If something needs to be looked up in the current docs, go ahead and check online. Keep it clean, practical, and ready to deploy.