Fix browser phone issues and improve UI organization

- Fix 403 Forbidden error in voicemail AJAX by correcting nonce validation
- Create accordion-style collapsible voicemail section with persistent state
- Restructure queue controls to show alert toggle button consistently
- Add global queue actions always visible when user has assigned queues
- Implement smooth slide animations and localStorage state management
- Update dark mode support for new UI elements and improved accessibility

🤖 Generated with [Claude Code](https://claude.ai/code)

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

admin/class-twp-admin.php

@@ -3774,7 +3774,7 @@ class TWP_Admin {
      * AJAX handler for getting user's recent voicemails
      */
     public function ajax_get_user_voicemails() {
-        check_ajax_referer('twp_ajax_nonce', 'nonce');
+        check_ajax_referer('twp_frontend_nonce', 'nonce');
         
         if (!current_user_can('manage_options') && !current_user_can('twp_access_voicemails')) {
             wp_send_json_error('Unauthorized');