[FIX] Migration SQL: INT NOT NULL per FK verso organizations/users (signed)

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

docs/sql/008_whistleblowing.sql

@@ -5,7 +5,7 @@
 
 CREATE TABLE IF NOT EXISTS whistleblowing_reports (
     id               INT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
-    organization_id  INT UNSIGNED NOT NULL,
+    organization_id  INT NOT NULL,
     report_code      VARCHAR(20) NOT NULL UNIQUE,          -- Es. WB-2026-001
 
     -- Mittente (opzionale — anonimato garantito)