[FIX] Database::execute() → Database::query() in 5 controller

Database non ha metodo execute() — corretto in:
InviteController, ServicesController, WebhookController,
NormativeController, WhistleblowingController.
Causa del HTTP 500 su tutti gli endpoint /api/invites/*.

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

application/controllers/NormativeController.php

@@ -124,7 +124,7 @@ class NormativeController extends BaseController
 
         if ($existing) {
             // Aggiorna note se già ACK
-            Database::execute(
+            Database::query(
                 'UPDATE normative_ack SET notes = ?, acknowledged_by = ?, acknowledged_at = NOW()
                  WHERE normative_update_id = ? AND organization_id = ?',
                 [$notes ?: null, $this->getCurrentUserId(), $id, $orgId]