The api.js library-list fix from the previous commit never reached the browser because nginx served all .js with `Cache-Control: public, immutable; max-age=31536000`. The HTML referenced api.js with no version query, so the browser kept its year-cached buggy copy.
* nginx.conf: drop .js from the immutable long-cache block, add a no-cache must-revalidate block so future redeploys are picked up immediately.
* All HTML files: tag api.js refs with ?v=4 so already-running browsers fetch the new version on next page load.
