certbot removed ssl-dhparams.pem from its repository, so the managed-nginx
startup failed with HTTP 404 on fresh installations (the legacy script only
kept working through its year-old state-dir cache). The RFC 7919 ffdhe2048
parameters are now a classpath resource; the download seam and
NginxConfigFiles.DH_PARAMS_URL are gone.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
