Adds Kubernetes-style /api/healthz endpoint with status/version/uptime_seconds/timestamp.
Non-breaking — /api/health preserved. Includes unit test (passes locally) and BDD scenario (validated by CI).
Généré ~95% en autonomie par Mistral Vibe via workspace ICM ~/Work/Vibe/workspaces/healthz-feature/.
Co-authored-by: Gabriel Radureau <arcodange@gmail.com>
Co-committed-by: Gabriel Radureau <arcodange@gmail.com>
