refactor: extract shared utilities and standardize page patterns

- Add fmtBytes() and csvToArr() helpers to hoover/helpers.js
- Replace inline async patterns with ActionButton/ConfirmDelete in wireguard.js
- Convert addDomain/editDomain to QuickModal + apiSubmit in proxy.js
- Convert settingsModal handlers to formAction in certs.js
- Remove redundant synced handling from dhcp.js apply button
- Add onComplete callback to ConfirmDelete (fixes users.js onRefresh bug)
- Fix passkeys.js ActionCell/Table usage (invalid component API)
- Remove duplicate fmtBytes from dashboard.js

webui/static/pages/dhcp.js

@@ -1,4 +1,4 @@
-import { html, h, PageHeader, ConfirmDelete, Tabs, Table, ServiceStatus, renderGuardMulti, esc, enc, $val, apiFetch, toast, definePage, getModel, modelFetch, ActionButton, ActionGroup, QuickModal } from '/static/hoover/index.js';
+import { html, h, PageHeader, ConfirmDelete, Tabs, Table, ServiceStatus, renderGuardMulti, esc, enc, $val, apiFetch, toast, definePage, getModel, modelFetch, ActionButton, ActionGroup, QuickModal, ApplyConfirm } from '/static/hoover/index.js';
 
 function makeAddRange(activeZones, interfaces) {
     const opts = [
@@ -209,13 +209,7 @@ export default definePage({
                     'on:click': async () => {
                         const res = await apiFetch('/api/dhcp/apply', { method: 'POST' });
                         if (res.ok) {
-                            const synced = res.data?.synced;
-                            let msg = 'dnsmasq applied';
-                            if (synced && synced.length) {
-                                msg += ' (auto-synced: ' + synced.join(', ') + ')';
-                                synced.forEach(s => modelFetch(s));
-                            }
-                            toast(msg, 'success');
+                            toast('dnsmasq applied', 'success');
                             modelFetch('dnsmasq');
                         } else {
                             toast(res.error || 'Apply failed', 'error');