The tab bar uses Unraid's localURL, which swaps content by AJAX without
tearing down the previous page's JavaScript, so old copies keep their timers
and their state. That makes "is the browser running what I deployed"
unanswerable from the server, and explains banner polls arriving far faster
than the 30s timer. The page now stamps its build, says plainly when its own
script is not the one running, and stops the previous copy's timers.