Merge pull request 'feat: save-on-pause via visibilitychange and beforeunload (#57)' (#69) from polish into main

Merge PR #69: feat: save-on-pause via visibilitychange

js/main.js

@@ -99,3 +99,13 @@ window.addEventListener('keydown', function (e) {
         saveGame();
     }
 });
+
+// Save-on-pause: auto-save when tab is hidden or closed (#57 Mobile Polish)
+document.addEventListener('visibilitychange', function () {
+    if (document.hidden) {
+        saveGame();
+    }
+});
+window.addEventListener('beforeunload', function () {
+    saveGame();
+});