Guard lt.* calls when base.js unavailable to prevent crash

Wraps all lt.keys.initDefaults() calls in `if (window.lt)` guards across
6 view files. Adds `if (!window.lt) return` bail-out in keyboard-shortcuts.js
and `if (window.lt)` guard in settings.js DOMContentLoaded handler.

This prevents TypeError crashes when /web_template/base.js returns 404,
which was causing the admin menu click delegation to never register.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

views/TicketView.php

@@ -816,6 +816,6 @@ $nonce = SecurityHeadersMiddleware::getNonce();
 
     <script nonce="<?php echo $nonce; ?>" src="<?php echo $GLOBALS['config']['ASSETS_URL']; ?>/js/keyboard-shortcuts.js"></script>
     <script nonce="<?php echo $nonce; ?>" src="<?php echo $GLOBALS['config']['ASSETS_URL']; ?>/js/settings.js"></script>
-    <script nonce="<?php echo $nonce; ?>">lt.keys.initDefaults();</script>
+    <script nonce="<?php echo $nonce; ?>">if (window.lt) lt.keys.initDefaults();</script>
 </body>
 </html>