Refactor admin panel: enhance user management and security features

- Added role-based access control for user management links in admin navigation.
- Improved user account display with a dedicated account link.
- Implemented form submission confirmation for delete actions in the admin interface.
- Introduced a password visibility toggle on the login page.
- Added login throttling to prevent brute-force attacks, recording failed attempts.
- Created a CLI script for creating an admin user, replacing the previous hardcoded admin credentials.
- Updated database schema to support login attempt tracking.
- Enhanced user editing functionality, allowing role changes with restrictions.
- Improved modal handling for user actions, ensuring better focus management.
- Added styles for new account management page and improved modal transitions.

admin/hours.php

@@ -87,12 +87,14 @@ $justSaved = !$_POST && isset($_GET['saved']);
       <div class="admin-nav-links">
         <a href="index.php">Announcements</a>
         <a href="menu.php">Menu</a>
+        <?php if (($user['role'] ?? '') === 'admin'): ?>
         <a href="users.php">Users</a>
+        <?php endif; ?>
         <a href="hours.php" class="active">Hours</a>
       </div>
       <div class="admin-user">
-        <span>Logged in as <strong><?= htmlspecialchars($user['username']) ?></strong></span>
         <a href="../" target="_blank" rel="noopener">View Public Site ↗</a>
+        <a href="account.php" class="admin-account-link" title="My Account"><?= htmlspecialchars($user['username']) ?></a>
         <a href="logout.php">Sign Out</a>
       </div>
     </div>