[FIX] SIM-06 + EmailService + WebhookService + supplier assessment

- ServicesController::provision(): created_by usa userId (INT) non string
- EmailService::logEmail(): rimosso sent_at (colonna non esiste in email_log)
- WebhookService::incidentPayload(): status ?? 'detected' (null-safe)
- simulate-nis2.php: supplier assessment usa formato assessment_responses
  corretto [{question, weight, value: yes|partial|no}]

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

application/services/EmailService.php

@@ -609,7 +609,6 @@ class EmailService
                 'recipient'  => $to,
                 'subject'    => mb_substr($subject, 0, 255),
                 'status'     => $success ? 'sent' : 'failed',
-                'sent_at'    => date('Y-m-d H:i:s'),
             ]);
         } catch (\Throwable $e) {
             error_log('[EmailService] Errore log email: ' . $e->getMessage());