fix(ui): Integrate webhooks panel into status panel

The webhooks panel was appearing separately from the status panel.
Now it's properly nested inside the status-panel div:

- Moved webhooks-section inside status-panel in HTML
- Updated CSS so nested webhooks looks like a subsection (no double borders)
- Simplified JS toggle logic - webhooks shows/hides automatically with status panel
- Admin users see webhooks inside status panel, collapsed by default

public/app.js

@@ -772,20 +772,22 @@ async function toggleStatusPanel() {
   const panel = document.getElementById('status-panel');
   const webhooksSection = document.getElementById('webhooks-section');
   if (panel.style.display !== 'none') {
+    // Close both panels (webhooks is nested, but hide explicitly)
     panel.style.display = 'none';
-    if (webhooksSection) webhooksSection.style.display = 'none';
     if (statusRefreshHandle) { clearInterval(statusRefreshHandle); statusRefreshHandle = null; }
     return;
   }
+  // Open status panel (contains webhooks nested inside)
   panel.style.display = 'block';
   // Show webhooks section for admin users (collapsed by default)
   if (webhooksSection && isAdmin) {
-    webhooksSection.style.display = '';
-    // Ensure webhooks section starts collapsed
+    webhooksSection.style.display = 'block';
     webhookSectionExpanded = false;
     document.getElementById('webhooks-content').style.display = 'none';
     document.getElementById('webhooks-toggle').classList.remove('expanded');
     await fetchWebhookStatus();
+  } else if (webhooksSection) {
+    webhooksSection.style.display = 'none';
   }
   await refreshStatusPanel();
   if (statusRefreshHandle) clearInterval(statusRefreshHandle);
@@ -794,8 +796,6 @@ async function toggleStatusPanel() {
 
 function closeStatusPanel() {
   document.getElementById('status-panel').style.display = 'none';
-  const webhooksSection = document.getElementById('webhooks-section');
-  if (webhooksSection) webhooksSection.style.display = 'none';
   if (statusRefreshHandle) { clearInterval(statusRefreshHandle); statusRefreshHandle = null; }
 }