The poller's forge, authelia and collector calls go to leaves issued by
the swarm's own CA, and its reqwest/rustls roots come from SSL_CERT_FILE,
which the unit never set. Every pass since it was deployed fails
"invalid peer certificate: UnknownIssuer" before pushing, so the CI runs
dashboard has no hyperhive.ci.run.* samples (#5438).
- nix/host-modules/swarm-ci-metrics.nix: import lib/hive-ca-trust.nix and
register a host trustBundle for the unit, as swarm-controller does; it
adds swarm-ci-metrics-ca-bundle.service and sets SSL_CERT_FILE.
- nix/module-eval/ci-metrics.nix: a case asserting the unit's
SSL_CERT_FILE is its bundle path when self-signed, with the bundle
unit's ordering, and absent where the poller is off.
- docs/swarm/ci-metrics.md: how the poller trusts the swarm's CA.