Add Helm page with diagram - New Helm.md (FR): what Helm is, Helm 2/3 and Tiller, vocabulary (chart, template, values, release, repository, revision), the three essential commands, chart anatomy, templates + values (and precedence), revisions and rollback, main commands, when to use it, Helm vs Kustomize, best practices - New images/helm.svg (repositories -> chart (+values) -> Helm -> cluster release) - Add page to Home (item 21) and _Sidebar; update AGENTS.md page list and next steps