Legacy in-cluster gitea-http repos are archived (issue create 423). Route
the default ingestion backend to https://forgejo.coulomb.social with
the-custodian as the central automation task inbox.
Introduce Dockerfile, entrypoint, and k8s/railiance manifests for the
ArgoCD GitOps pilot (ISSUE-WP-0003). Rename the Gitea PyPI build arg to
GITEA_PYPI_INDEX_URL so pip still resolves dependencies from PyPI.
