Add mobile nav toggle, responsive admin tables, and menu reordering

- Public site: replace the always-hidden mobile nav with a hamburger
  toggle (index.php, menu.php, main.js, styles.css)
- Admin: render the Menu/Announcements/Users tables as labeled cards
  below ~760px instead of squeezing descriptions into unreadable
  single-word-per-line columns
- Admin menu: replace the manual "Order" number (which allowed
  duplicates and never reflected in real time) with ↑/↓ buttons that
  reorder items and categories immediately and renumber sort_order
  sequentially on every move, self-healing any stale duplicates

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

inc/menu.php

@@ -62,23 +62,64 @@ function category_exists(int $id): bool {
     return (bool)$stmt->fetchColumn();
 }
 
+// Categories are manually reordered via move_category() rather than a typed
+// sort_order field, so a new one always joins at the end of the list.
+function next_category_sort_order(): int {
+    $pdo = get_db();
+    return (int) $pdo->query("SELECT COALESCE(MAX(sort_order), -1) + 1 FROM menu_categories")->fetchColumn();
+}
+
 function save_category(array $data, ?int $id = null): int {
     $pdo = get_db();
     $name = trim($data['name'] ?? '');
     $description = trim($data['description'] ?? '');
-    $sortOrder = (int)($data['sort_order'] ?? 0);
 
     if ($id && $id > 0) {
-        $stmt = $pdo->prepare("UPDATE menu_categories SET name = ?, description = ?, sort_order = ? WHERE id = ?");
-        $stmt->execute([$name, $description, $sortOrder, $id]);
+        $stmt = $pdo->prepare("UPDATE menu_categories SET name = ?, description = ? WHERE id = ?");
+        $stmt->execute([$name, $description, $id]);
         return $id;
     } else {
+        $sortOrder = next_category_sort_order();
         $stmt = $pdo->prepare("INSERT INTO menu_categories (name, description, sort_order) VALUES (?, ?, ?)");
         $stmt->execute([$name, $description, $sortOrder]);
         return (int)$pdo->lastInsertId();
     }
 }
 
+/**
+ * Swap a category with its previous/next neighbor (by current display
+ * order) and renumber every category's sort_order sequentially from 0.
+ * The renumbering is what keeps values unique and gap-free — it also
+ * self-heals any duplicate/stale sort_order left over from before this
+ * existed, since the new numbers come purely from display position.
+ */
+function move_category(int $id, string $direction): array {
+    $pdo = get_db();
+    $orderedIds = $pdo->query("SELECT id FROM menu_categories ORDER BY sort_order ASC, id ASC")
+        ->fetchAll(PDO::FETCH_COLUMN);
+
+    $index = array_search($id, $orderedIds, true);
+    if ($index === false) {
+        return ['success' => false, 'error' => 'Category not found.'];
+    }
+
+    $swapWith = $direction === 'up' ? $index - 1 : $index + 1;
+    if ($swapWith < 0 || $swapWith >= count($orderedIds)) {
+        return ['success' => false, 'error' => 'Category is already at the ' . ($direction === 'up' ? 'top' : 'bottom') . '.'];
+    }
+
+    [$orderedIds[$index], $orderedIds[$swapWith]] = [$orderedIds[$swapWith], $orderedIds[$index]];
+
+    $update = $pdo->prepare("UPDATE menu_categories SET sort_order = ? WHERE id = ?");
+    $pdo->beginTransaction();
+    foreach ($orderedIds as $position => $categoryId) {
+        $update->execute([$position, $categoryId]);
+    }
+    $pdo->commit();
+
+    return ['success' => true];
+}
+
 function delete_category(int $id): bool {
     $pdo = get_db();
     $stmt = $pdo->prepare("DELETE FROM menu_categories WHERE id = ?");
@@ -93,6 +134,15 @@ function get_menu_item_by_id(int $id): ?array {
     return $res ?: null;
 }
 
+// Items are manually reordered via move_menu_item() rather than a typed
+// sort_order field, so a new one always joins at the end of its category.
+function next_item_sort_order(int $categoryId): int {
+    $pdo = get_db();
+    $stmt = $pdo->prepare("SELECT COALESCE(MAX(sort_order), -1) + 1 FROM menu_items WHERE category_id = ?");
+    $stmt->execute([$categoryId]);
+    return (int) $stmt->fetchColumn();
+}
+
 function save_menu_item(array $data, ?int $id = null): int {
     $pdo = get_db();
     $categoryId = (int)($data['category_id'] ?? 0);
@@ -101,18 +151,27 @@ function save_menu_item(array $data, ?int $id = null): int {
     $price = trim($data['price'] ?? '');
     $badge = trim($data['badge'] ?? '');
     $isAvailable = !empty($data['is_available']) ? 1 : 0;
-    $sortOrder = (int)($data['sort_order'] ?? 0);
 
     if ($id && $id > 0) {
+        $existing = get_menu_item_by_id($id);
+        // Keep its existing position when the category is unchanged; if the
+        // item was reassigned to a different category, it joins at the end
+        // of that category rather than keeping a sort_order that was only
+        // ever meaningful among its old category's items.
+        $sortOrder = ($existing && (int) $existing['category_id'] === $categoryId)
+            ? (int) $existing['sort_order']
+            : next_item_sort_order($categoryId);
+
         $stmt = $pdo->prepare("
-            UPDATE menu_items SET 
-                category_id = ?, name = ?, description = ?, price = ?, 
+            UPDATE menu_items SET
+                category_id = ?, name = ?, description = ?, price = ?,
                 badge = ?, is_available = ?, sort_order = ?, updated_at = CURRENT_TIMESTAMP
             WHERE id = ?
         ");
         $stmt->execute([$categoryId, $name, $description, $price, $badge, $isAvailable, $sortOrder, $id]);
         return $id;
     } else {
+        $sortOrder = next_item_sort_order($categoryId);
         $stmt = $pdo->prepare("
             INSERT INTO menu_items (category_id, name, description, price, badge, is_available, sort_order)
             VALUES (?, ?, ?, ?, ?, ?, ?)
@@ -122,6 +181,45 @@ function save_menu_item(array $data, ?int $id = null): int {
     }
 }
 
+/**
+ * Swap a menu item with its previous/next neighbor within its own category
+ * (by current display order) and renumber that category's items
+ * sequentially from 0. See move_category() for why renumbering matters.
+ */
+function move_menu_item(int $id, string $direction): array {
+    $item = get_menu_item_by_id($id);
+    if (!$item) {
+        return ['success' => false, 'error' => 'Menu item not found.'];
+    }
+
+    $pdo = get_db();
+    $categoryId = (int) $item['category_id'];
+    $stmt = $pdo->prepare("SELECT id FROM menu_items WHERE category_id = ? ORDER BY sort_order ASC, id ASC");
+    $stmt->execute([$categoryId]);
+    $orderedIds = $stmt->fetchAll(PDO::FETCH_COLUMN);
+
+    $index = array_search($id, $orderedIds, true);
+    if ($index === false) {
+        return ['success' => false, 'error' => 'Menu item not found.'];
+    }
+
+    $swapWith = $direction === 'up' ? $index - 1 : $index + 1;
+    if ($swapWith < 0 || $swapWith >= count($orderedIds)) {
+        return ['success' => false, 'error' => 'Item is already at the ' . ($direction === 'up' ? 'top' : 'bottom') . '.'];
+    }
+
+    [$orderedIds[$index], $orderedIds[$swapWith]] = [$orderedIds[$swapWith], $orderedIds[$index]];
+
+    $update = $pdo->prepare("UPDATE menu_items SET sort_order = ? WHERE id = ?");
+    $pdo->beginTransaction();
+    foreach ($orderedIds as $position => $itemId) {
+        $update->execute([$position, $itemId]);
+    }
+    $pdo->commit();
+
+    return ['success' => true];
+}
+
 function toggle_menu_item_availability(int $id): bool {
     $pdo = get_db();
     $stmt = $pdo->prepare("UPDATE menu_items SET is_available = CASE WHEN is_available = 1 THEN 0 ELSE 1 END, updated_at = CURRENT_TIMESTAMP WHERE id = ?");