Set up CI/publish pipelines for tes, workflow-bundles, api-gateway

[man4ish]

None of these three repos currently have a working CI pipeline
(.github/workflows is empty in all three). omnibioai-studio has a
release.yml but it's sitting in a disabled/ subfolder and doesn't run.

This means merges to main don't automatically build or publish new
images to ghcr.io. Right now:

• tes and workflow-bundles build from local source in dev, so they
  pick up main on the next docker compose build — no registry
  dependency for local dev.
• api-gateway is the one real risk: it's pulled from
  ghcr.io/omnibioai/omnibioai-api-gateway:latest with no local build
  context. A fix merged to main will NOT be reflected in the running
  image until someone does a real CI build+push (or reactivates
  studio's disabled release.yml for this repo). Until then, a plain
  docker compose pull will silently revert to the pre-fix image
  with no error or warning.

Needs: either a minimal build-and-push GitHub Actions workflow for
api-gateway (and ideally tes/workflow-bundles too, for consistency),
or reactivating/adapting studio's existing disabled release.yml
pattern for these repos.

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