Fix vital signs age selector: add setTimeout for DOM readiness

public/js/calculators.js

@@ -1595,6 +1595,8 @@
       }
     };
 
+    // Delay slightly to ensure DOM is ready for hidden panels
+    setTimeout(function() {
     var vitalsSelect = document.getElementById('vitals-age-select');
     if (vitalsSelect) {
       vitalsSelect.addEventListener('change', function() {
@@ -1626,5 +1628,6 @@
           '</div>';
       });
     }
+    }, 100); // end setTimeout for vitals
   }
 })();