feat(images): build, verify and publish the three images in CI; Renovate carries the digests

Operator rule 2026-10-29: image creation, hosting and lifecycle belong to CI/CD, never to a
workstation build/push. Nothing had ever been pushed to the Gitea registry.

- .gitea/workflows/images.yaml + scripts/images.sh: PRs build+verify (no credential); main
  builds, verifies and pushes toolbox, agent-runner (FROM toolbox) and conformance-runner as
  sha-<commit> + main, reading the digest back from the registry. Only changed images build.
- Each image's own build-image.sh does the build and in-image verification, now engine-neutral
  (DinD: no podman-only calls, probe over stdin not a bind mount). New toolbox build-image.sh.
- Digest references carry `# renovate-digest:` markers; renovate.json5 gains a custom.regex
  manager for them. The worker Job template is deliberately untracked (it would loop).
- renovate.yaml pins renovate-version 44.167.0: the action's default (39.264.0) rejects the
  current config's managerFilePatterns, so every run would have died at CONFIG_VALIDATION.
- Push credential: REGISTRY_PUSH_TOKEN secret; the Actions token has no package scope in
  Gitea 1.24.3 (container.go Authenticate). Retention: infra/gitea/registry-retention.sh.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

runbooks/pm-agent.md

@@ -67,10 +67,10 @@ Work through these in order; the first three are by far the most likely.
 | Symptom in the log | Cause | Fix |
 |---|---|---|
 | `GET /user returned no login — is GITEA_TOKEN valid?` and a CrashLoop | the credentials are still the committed **placeholders**, or the token was revoked | fill them in per `platform/pm-agent/pm-agent-credentials.sops.yaml.example` |
-| `ImagePullBackOff`, digest `sha256:0000…` | the image has never been pushed; the committed digest is the deliberate placeholder | `infra/agent/build-image.sh`, operator pushes, then one PR updates the digest in **both** `deployment.yaml` and `configmap.yaml` (`PM_WORKER_IMAGE`) — but read the row below first |
+| `ImagePullBackOff`, digest `sha256:0000…` | the image has never been published; the committed digest is the deliberate placeholder | CI publishes it, not a person: check the latest `images` workflow run on `main` (it fails loudly if the `REGISTRY_PUSH_TOKEN` secret is missing; re-run it with `workflow_dispatch`), then merge Renovate's digest-bump PR, which updates **both** `deployment.yaml` and `configmap.yaml` (`PM_WORKER_IMAGE`) together — but read the row below first |
 | `ImagePullBackOff` with `x509: certificate is not valid for any names` | **diagnosed.** containerd pulls as a node process, resolves through the node's public upstreams, and gets the CNAME to the WAN IP — which this router does not hairpin, so it answers :443 with its own `CN=%D` placeholder certificate (no SANs at all). Nothing to do with the digest, the Gateway or the wildcard cert | the `/etc/hosts` pin for `gitea.{{ k3s_base_domain }}` → `192.168.2.20` in `infra/ansible/inventory/group_vars/k3s_prod/vars.yml` fixes it — the same pin the Keycloak issuer already has. Apply it with the project's own tooling, scoped to just that task: `cd infra/ansible && ansible-playbook playbooks/node-baseline.yml -e k3s_hosts=k3s_prod --tags hosts`. Full evidence: `decisions/2026-10-06-pm-agent-node-resolves-gitea-to-wan.md` |
 | `ImagePullBackOff` with `401 Unauthorized` once TLS works | the pull is unauthenticated. An anonymous client gets nothing from this Gitea's registry, and no `imagePullSecret` exists anywhere in the tree | add one (a `dockerconfigjson`, SOPS-encrypted like `pm-agent-credentials`, referenced from the Deployment **and** the committed worker Job template) or allow anonymous reads of the package in Gitea — a posture decision, so yours |
-| `PM_WORKER_IMAGE must be digest-pinned` | someone put a tag in the ConfigMap | use the digest from `podman push --digestfile` |
+| `PM_WORKER_IMAGE must be digest-pinned` | someone put a tag in the ConfigMap | restore the digest form; the digest comes from CI's publish (`.gitea/workflows/images.yaml` job summary) and Renovate's bump PR, never from a hand push |
 | `scope: ONLY issues labelled 'agent'` | `PM_REQUIRE_LABEL` is set; unlabelled issues are out of scope by configuration | label the issue, or clear the knob |
 | `cycle: 2 worker(s) active` and nothing new | at `PM_MAX_ACTIVE_WORKERS` | wait, or raise it (RAM is the binding constraint: each worker's limit is 2Gi) |
 | `at the worker cap` / `worker limit reached` | the per-cycle cap, draining a backlog one issue at a time | expected; it will continue next cycle |