fix(infra): bake config into images so compose-smoke passes on CI (refs #30)

Root cause of the compose-smoke failure (found in the runner logs):

  oz-init-1 | CommandError: Yaml file
              `/app/setup_configuration/data.yaml` does not exist.

The ubuntu-latest runner runs the job inside a container, so
`docker compose up` starts the stack as SIBLING containers via the host
daemon. A relative bind mount (./openzaak/setup_configuration) resolves to
a path inside the job container that the daemon can't see, so Docker mounts
an empty dir and the init container can't find data.yaml. The same trap hit
nrc-init (data.yaml), flowable-init (the BPMN) and keycloak (realm import).

Fix: bake the assets into small derived images instead of bind-mounting:
  - infra/openzaak/Dockerfile        -> register-referentie/openzaak:dev
  - infra/opennotificaties/Dockerfile-> register-referentie/opennotificaties:dev
  - infra/keycloak/Dockerfile        -> register-referentie/keycloak:dev
  - flowable-init: build.dockerfile_inline bakes workflows/registratie.bpmn

Base versions stay build args (OPENZAAK_TAG / OPENNOTIFICATIES_TAG), so the
pinning is unchanged. Applied to both the consolidated compose and the
per-service composes, so local Podman and CI use one mechanism — no bind
mounts, no SELinux `:z`, no world-readable requirement.

Verified locally: `podman build` of the OpenZaak and BPMN images produces
the file at the expected in-container path.

Docs: docs/runbooks/gitea-actions-gotchas.md explains the DinD bind-mount
trap and the bake fix; openzaak.md and ci.md point at it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/runbooks/openzaak.md

@@ -71,5 +71,9 @@ The Makefile auto-points `DOCKER_HOST` at the Podman socket when it exists, so t
   but OZ→NRC delivery wiring + re-enabling lands with **S-06**.
 - **Zaaktype is a concept**, not published (publishing needs roltypen/statustypen/
   resultaattypen — beyond the lean seed). List with `?status=alles`.
-- **Image tag.** Currently `openzaak/open-zaak:latest` via `${OPENZAAK_TAG}`; pin to
-  a known-good tag (ADR-0002 follow-up).
+- **Image tag.** Pinned to `openzaak/open-zaak:1.28.2` via `${OPENZAAK_TAG}` (bump
+  deliberately, not via `:latest`).
+- **Config is baked, not mounted.** `setup_configuration/data.yaml` is `COPY`-ed into
+  a derived image (`infra/openzaak/Dockerfile`) rather than bind-mounted, so the
+  init container finds it on Gitea's containerized CI runner too. See
+  [gitea-actions-gotchas.md](gitea-actions-gotchas.md).