Fix workflow forward task immediate disconnection issue

Fixed critical bug where forward tasks in workflows would immediately disconnect calls instead of forwarding them properly.

Changes:
- Fixed append_twiml_element function to properly handle Dial elements with child Number elements
- Enhanced create_forward_twiml to extract numbers from nested data structures
- Added comprehensive error handling for missing forward numbers
- Added detailed logging throughout workflow execution for debugging
- Set default timeout of 30 seconds for forward operations

The issue was caused by the Dial element being converted to string which lost all child Number elements, resulting in an empty dial that would immediately disconnect.

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

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

includes/class-twp-core.php

@@ -161,6 +161,7 @@ class TWP_Core {
         
         // Eleven Labs AJAX
         $this->loader->add_action('wp_ajax_twp_get_elevenlabs_voices', $plugin_admin, 'ajax_get_elevenlabs_voices');
+        $this->loader->add_action('wp_ajax_twp_refresh_elevenlabs_voices', $plugin_admin, 'ajax_refresh_elevenlabs_voices');
         $this->loader->add_action('wp_ajax_twp_get_elevenlabs_models', $plugin_admin, 'ajax_get_elevenlabs_models');
         $this->loader->add_action('wp_ajax_twp_preview_voice', $plugin_admin, 'ajax_preview_voice');