Fix: session_start et requête SQL id_conversation

enseignant/chatbot_api_ajax.php

@@ -4,7 +4,6 @@
  * Actions : save, test, delete, get
  */
 
-session_start();
 header('Content-Type: application/json');
 
 require_once '../config/config.php';

enseignant/chatbot_api_settings.php

@@ -4,7 +4,6 @@
  * Interface de gestion pour les enseignants
  */
 
-session_start();
 require_once '../config/config.php';
 require_once '../config/database.php';
 require_once '../config/session.php';
@@ -35,7 +34,7 @@ foreach ($all_models as $model) {
 // Récupérer les statistiques d'utilisation
 $stats = $db->fetchOne(
     "SELECT 
-        COUNT(DISTINCT id_conversation) as total_conversations,
+        COUNT(DISTINCT id) as total_conversations,
         SUM(total_messages) as total_messages,
         provider,
         model_used