SECRET_KEY pulled from node metadata (set via !32_random_bytes_as_base64_for:
in the node file). SESSION_COOKIE_SECURE flips to true since nginx fronts
gunicorn with TLS.
Copied verbatim from left4me/deploy/files/. Helpers are the trust unit
the sudoers rules grant access to; left as static files (not generated)
so the audit trail stays grep-able. Modes/owners are set via items.py
in the next commit.