fix(kubernetes): use published release candidates for portable labs

[fabricebrito]

Chapter 5 must run with published images on a configured Kubernetes cluster. This replaces the Minikube-local defaults with a selected published CWL release and matching inputs.

• Add manual candidate publication with unique prerelease versions, preserving the stable release version and latest-release designation.
• Include typed scatter inputs in release assets; download and validate the CWL and inputs together before preparing the lab volume.
• Reject local image references and mismatched package versions; update both notebooks, benchmark setup, and release guidance.

Validation: eight focused metadata/download checks passed, real cwltool validation of packed CWL and typed inputs passed, actionlint and strict MkDocs builds passed. Candidate registry publication and Kubernetes execution are the next integration checks.