Add comprehensive queue management to browser phone shortcode

Features Added:
- Queue display showing all assigned queues for the current user
- Real-time queue statistics (waiting calls, capacity)
- Visual indicators for queues with waiting calls (green border, pulse animation)
- Queue selection with click interaction
- Accept next call from selected queue functionality
- Auto-refresh of queue data every 30 seconds
- Mobile-responsive queue interface

Backend Changes:
- New ajax_get_agent_queues() handler to fetch user's assigned queues
- Enhanced ajax_get_waiting_calls() to return structured data
- Proper permission checking for twp_access_agent_queue capability

Frontend Enhancements:
- Interactive queue list with selection states
- Queue controls panel showing selected queue info
- Refresh button for manual queue updates
- Visual feedback for queues with active calls
- Mobile-optimized layout for smaller screens

UI/UX Improvements:
- Queues with waiting calls highlighted with green accent
- Pulsing indicator for active queues
- Auto-selection of first queue with calls
- Responsive design for mobile devices
- Dark mode support for queue elements

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

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

includes/class-twp-core.php

@@ -174,6 +174,7 @@ class TWP_Core {
         $this->loader->add_action('twp_check_queue_timeouts', $this, 'check_queue_timeouts');
         $this->loader->add_action('wp_ajax_twp_accept_next_queue_call', $plugin_admin, 'ajax_accept_next_queue_call');
         $this->loader->add_action('wp_ajax_twp_get_waiting_calls', $plugin_admin, 'ajax_get_waiting_calls');
+        $this->loader->add_action('wp_ajax_twp_get_agent_queues', $plugin_admin, 'ajax_get_agent_queues');
         $this->loader->add_action('wp_ajax_twp_set_agent_status', $plugin_admin, 'ajax_set_agent_status');
         $this->loader->add_action('wp_ajax_twp_get_call_details', $plugin_admin, 'ajax_get_call_details');