Add pub hours admin panel, rebuild announcements/users lists on CSS Grid

- Add a Hours admin panel (admin/hours.php, admin/hours.js) for editing
  the weekly open/close schedule and an optional per-day kitchen closing
  time, with a live preview of how it'll read on the public site
- Store hours in a new pub_hours table (inc/db.php), seeded with the
  site's existing Thu-Sat/9pm-kitchen schedule; inc/hours.php formats
  and groups it for display (day ranges, kitchen-close note, footer
  summary)
- Wire the public Visit card and both site footers (index.php, menu.php)
  to read hours from that data instead of hardcoded copy
- Rebuild the Announcements and Users admin tables onto the same CSS
  Grid list pattern already used for the Menu (admin-table-actions ->
  row-actions), and make the Announcements status toggle an in-place
  AJAX action like the menu item's (admin/index.js)
- Add the Hours tab to admin nav across all four admin pages

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

admin/index.js

@@ -0,0 +1,34 @@
+// Announcements admin page: intercepts the status badge's toggle form so
+// clicking it updates in place via fetch instead of reloading the whole
+// page — same interaction as the menu item's status toggle. Everything
+// else here (create/edit/delete) is still a plain form POST + reload.
+
+document.addEventListener('submit', async (e) => {
+  const form = e.target;
+  if (!form.classList.contains('status-toggle-form')) return;
+
+  e.preventDefault();
+  const btn = form.querySelector('button');
+  btn.disabled = true;
+
+  try {
+    const response = await fetch('index.php', {
+      method: 'POST',
+      body: new FormData(form),
+      headers: { 'X-Requested-With': 'XMLHttpRequest' }
+    });
+    const data = await response.json();
+
+    if (data.success) {
+      btn.className = `status-badge ${data.status_class}`;
+      btn.textContent = data.status_label;
+      btn.title = `Click to turn ${data.is_active ? 'off' : 'on'}`;
+    } else {
+      alert(data.error || 'Failed to update status.');
+    }
+  } catch {
+    alert('Network error. Please try again.');
+  } finally {
+    btn.disabled = false;
+  }
+});