samyk/evercookie ? reverse-engineered prompt

Build me a working demo of Evercookie, a browser cookie system that tries to keep the same ID even after normal cookies are cleared.

I want a simple page that lets me set, read, and clear a user identifier, then shows which browser storage methods are available and which ones are being used. Please include the client side JavaScript and the PHP backend pieces needed for the cache, ETag, and image based storage tricks, so the whole thing runs locally. Make it easy to open the main page in a browser and see the behavior right away.

Keep the UI simple, like a small test page with a few buttons and a visible status area. If some older browser features are missing, it should still work with the ones that are available. Please make the code clean and easy to follow, and if you need current browser or PHP details, look up the latest docs online first.