Docker deployments have no .env file — settings live in container env
vars — so the export now writes env-snapshot.env (dotenv format) into
the data dir from a whitelist of portable keys (admin password, Resend
keys, webhook URLs, etc.) before archiving. Machine-specific vars
(PORT, NODE_ENV, SITEFORGE_DATA_DIR, ALLOW_INSECURE_COOKIES, build
metadata) are excluded. Values are not applied automatically on
restore; the file documents what to set on the new server.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>