The Gitea Actions runners on Legion need build containers to be able
to clone repos. They run with network: host so they can't resolve
gitea.git.svc.cluster.local — they have to use the public URL. The
public URL sits behind Cloudflare Access, which is why the previous
naive switch (#3) had to be reverted.
This change keeps the runner daemon registered against the in-cluster
URL (no CF Access on the polling loop) but rewrites
http://gitea.git.svc.cluster.local:3000/ to
https://git.neuralplatform.ai/ inside the build container, with the
CF Access service-token headers injected via git extraHeader.
The redirect script is sourced before every job step via BASH_ENV;
the CF Access credentials reach the build container through
act_runner's container.env, which we now populate from the new
gitea-runner-cf-access Vault path that PR #5's Terraform writes.
Known limitation documented in the init script: actions/checkout's
per-job auth header is keyed to the in-cluster URL and gets dropped
after the insteadOf rewrite. Public repos work; private repos that
need that token will need a follow-up.