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>

inc/db.php

@@ -77,6 +77,15 @@ function init_db_schema(PDO $pdo): void {
             sort_order INTEGER NOT NULL DEFAULT 0,
             updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
         );
+
+        CREATE TABLE IF NOT EXISTS pub_hours (
+            day_of_week INTEGER PRIMARY KEY,
+            is_open INTEGER NOT NULL DEFAULT 0,
+            open_time TEXT NULL,
+            close_time TEXT NULL,
+            kitchen_close_time TEXT NULL,
+            updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
+        );
     ");
 
     // Seed default admin user if table is empty (username: admin / password: password)
@@ -87,4 +96,33 @@ function init_db_schema(PDO $pdo): void {
         $insert = $pdo->prepare("INSERT INTO users (username, password_hash, role) VALUES (?, ?, 'admin')");
         $insert->execute(['admin', $defaultPassHash]);
     }
+
+    // Seed default weekly hours if the table is empty: closed Sun–Wed,
+    // 4–10pm Thu–Sat with the kitchen closing at 9 — matches the hours the
+    // site originally shipped with as hardcoded copy.
+    $stmt = $pdo->query("SELECT COUNT(*) as count FROM pub_hours");
+    $hoursCount = $stmt->fetchColumn();
+    if ($hoursCount == 0) {
+        $insert = $pdo->prepare("
+            INSERT INTO pub_hours (day_of_week, is_open, open_time, close_time, kitchen_close_time)
+            VALUES (?, ?, ?, ?, ?)
+        ");
+        // 0=Sunday ... 6=Saturday
+        $defaults = [
+            0 => null, // Sunday — closed
+            1 => null, // Monday — closed
+            2 => null, // Tuesday — closed
+            3 => null, // Wednesday — closed
+            4 => ['16:00', '22:00', '21:00'], // Thursday
+            5 => ['16:00', '22:00', '21:00'], // Friday
+            6 => ['16:00', '22:00', '21:00'], // Saturday
+        ];
+        foreach ($defaults as $day => $times) {
+            if ($times === null) {
+                $insert->execute([$day, 0, null, null, null]);
+            } else {
+                $insert->execute([$day, 1, $times[0], $times[1], $times[2]]);
+            }
+        }
+    }
 }