The redirect-to-flow design with an absolute cross-host next= was rejected by
the flow's open-redirect guard at completion ("Request has been denied:
Invalid next URL"), and meta-header routing does not exist in this build
(providers route on the ORIGINAL Host). :8016 now proxies every request whole
to authentik-server:9000 preserving Host; the embedded outpost serves login
in place and forwards authenticated traffic back to :8017. Requires one proxy
provider per guarded host (provisioned live: search/hermes/prometheus/romm/
files + www, flows backfilled). Tests flipped from the meta-header claim to
the upheld contract: Host preserved, no absolute next= redirects.