Add two missing security headers to the existing securityHeadersMiddleware:
- X-Content-Type-Options: nosniff — prevents browsers from MIME-sniffing
responses away from the declared Content-Type, stopping e.g. a
user-uploaded image from being reinterpreted as executable HTML/JS
- Referrer-Policy: strict-origin-when-cross-origin — limits URL information
leaked in the Referer header on cross-origin requests to just the origin
(no path), and sends nothing at all on HTTPS-to-HTTP downgrades