Update status checks and add optgroup support to form modals

- modal.js: add optgroup support for select options in formModal
- dhcp.js: use zone-based interface selector for DHCP ranges
- dashboard.js, wireguard.js: use status.up for state checks
- proxy.js: use inner.querySelector for modal field lookup

webui/static/pages/proxy.js

@@ -98,8 +98,8 @@ function addDomain(state) {
             },
         ]);
 
-        const certSelect = document.getElementById('p-cert');
-        const domainInput = document.getElementById('p-domain');
+        const certSelect = inner.querySelector('#p-cert');
+        const domainInput = inner.querySelector('#p-domain');
         if (certSelect && domainInput) {
             certSelect.addEventListener('change', () => {
                 const val = certSelect.value;