feat(phases): implement webhooks (6.1), email (7.1), user preferences (7.2)

- Phase 6.1: WebhookConfig model, CRUD router (/api/v1/webhooks, admin-only),
  dispatch_webhook() with HMAC signing; integrated into test validation,
  campaign completion, and MITRE sync job
- Phase 7.1: SMTP email service with send_test_validated_email,
  send_campaign_completed_email, send_new_mitre_techniques_email;
  notify_role_with_email() added to notification_service
- Phase 7.2: notification_preferences and jira_account_id on User model;
  PATCH /users/me/preferences endpoint; Alembic migrations b031phase6 and b032phase7

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

backend/app/jobs/mitre_sync_job.py

@@ -42,11 +42,13 @@ scheduler = BackgroundScheduler()
 
 def _run_mitre_sync() -> None:
     """Execute a MITRE sync inside its own DB session."""
+    from app.services.webhook_service import dispatch_webhook
     logger.info("Scheduled MITRE sync job starting...")
     db = SessionLocal()
     try:
         summary = sync_mitre(db)
         logger.info("Scheduled MITRE sync job finished — %s", summary)
+        dispatch_webhook("mitre.synced", {"created": summary.get("created", 0), "updated": summary.get("updated", 0)})
     except Exception:
         logger.exception("Scheduled MITRE sync job failed")
     finally: