fix: replace undefined text_edit panel heading with heading_title

text_edit is a global OC string not loaded in module language context,
causing the raw key to appear as the panel heading. Use heading_title
('Reverb Integration') which is already defined in the language file.

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

upload/admin/controller/extension/module/reverb.php

@@ -51,7 +51,6 @@ class ControllerExtensionModuleReverb extends Controller {
             $data[$key] = $this->language->get($key);
         }
         // Global OC strings
-        $data['text_edit']     = $this->language->get('text_edit');
         $data['text_enabled']  = $this->language->get('text_enabled');
         $data['text_disabled'] = $this->language->get('text_disabled');
         $data['button_save']   = $this->language->get('button_save');

upload/admin/view/template/extension/module/reverb.twig

@@ -35,7 +35,7 @@
 
     <div class="panel panel-default">
       <div class="panel-heading">
-        <h3 class="panel-title"><i class="fa fa-pencil"></i> {{ text_edit }}</h3>
+        <h3 class="panel-title"><i class="fa fa-cog"></i> {{ heading_title }}</h3>
       </div>
       <div class="panel-body">