Add tap-to-update button on version footer to force-refresh cached assets

Phones stuck on stale service-worker caches (esp. iOS home-screen PWAs) could
show the new version string while still running old app.js/css. Tapping the
footer now unregisters the service worker, clears all caches, and reloads to
pull the latest build.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "shelem",
-  "version": "1.1.3",
+  "version": "1.1.4",
   "description": "Shelem card game — multiplayer",
   "main": "server.js",
   "scripts": {