Fix voicemail and queue announcement issues

- Fixed phone agents getting 'Unauthorized' error when accessing voicemails by checking for twp_access_voicemails capability
- Fixed missing ElevenLabs parameter in queue TwiML generation that prevented announcement messages
- Fixed IVR voicemail messages not being saved correctly - now properly assigns message field based on action type
- Added proper permission checks for both ajax_get_voicemail and ajax_get_voicemail_audio functions

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

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

admin/class-twp-admin.php

@@ -3432,6 +3432,11 @@ class TWP_Admin {
     public function ajax_get_voicemail() {
         check_ajax_referer('twp_ajax_nonce', 'nonce');
         
+        if (!current_user_can('manage_options') && !current_user_can('twp_access_voicemails')) {
+            wp_send_json_error('Unauthorized');
+            return;
+        }
+        
         $voicemail_id = intval($_POST['voicemail_id']);
         
         if (!$voicemail_id) {
@@ -3487,7 +3492,7 @@ class TWP_Admin {
     public function ajax_get_voicemail_audio() {
         check_ajax_referer('twp_ajax_nonce', 'nonce');
         
-        if (!current_user_can('manage_options')) {
+        if (!current_user_can('manage_options') && !current_user_can('twp_access_voicemails')) {
             wp_send_json_error('Unauthorized');
             return;
         }