- Session and CSRF cookies are secure-only unless DEBUG is on.
- TRUST_X_FORWARDED_PROTO honours X-Forwarded-Proto from a TLS
terminating ingress. Without it, Django 4+ fails the CSRF origin
check on every form POST.
- CSRF_TRUSTED_ORIGINS, SECURE_SSL_REDIRECT and SECURE_HSTS_SECONDS are
configurable and off by default. HSTS for subdomains and preload are
left to ungleich, since they affect all of *.ungleich.ch.