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/menu.js

@@ -352,7 +352,7 @@ function itemRowHtml(item, isAvail) {
     <div data-label="Status"><button type="button" class="status-badge btn-toggle-item ${isAvail ? 'active' : 'inactive'}" data-id="${item.id}" title="Click to mark as ${isAvail ? 'sold out' : 'available'}">${isAvail ? '● Available' : '○ Sold Out'}</button></div>
     <div data-label="Item"><span class="item-name-row"><strong class="item-name-cell">${escapeHtml(item.name)}</strong>${badgeHtml}</span><div class="muted item-desc-cell">${escapeHtml(item.description || '')}</div></div>
     <div class="font-mono item-price-cell" data-label="Price">${escapeHtml(item.price)}</div>
-    <div data-label="Actions"><div class="admin-table-actions">
+    <div data-label="Actions"><div class="row-actions">
       <div class="action-stack">
         <button type="button" class="btn btn-outline btn-sm btn-icon btn-move-item" data-direction="up" aria-label="Move ${escapeHtml(item.name)} up">↑</button>
         <button type="button" class="btn btn-outline btn-sm btn-icon btn-move-item" data-direction="down" aria-label="Move ${escapeHtml(item.name)} down">↓</button>
@@ -432,7 +432,7 @@ function categoryPanelHtml(category) {
         <span>${escapeHtml(category.name)}</span>
       </h2>
       <p class="muted cat-desc-text">${escapeHtml(category.description || '')}</p>
-      <div class="admin-table-actions">
+      <div class="row-actions">
         <div class="action-stack">
           <button type="button" class="btn btn-outline btn-sm btn-icon btn-move-cat" data-direction="up" data-id="${category.id}" aria-label="Move category up">↑</button>
           <button type="button" class="btn btn-outline btn-sm btn-icon btn-move-cat" data-direction="down" data-id="${category.id}" aria-label="Move category down">↓</button>