Adds three lint jobs (actionlint, shellcheck, compose) and a server-side
dry-run of the active manifests. Previously the only k8s check was
kubeconform, which has no schemas for CRDs, so every IngressRoute,
Certificate, PrometheusRule and Middleware was silently skipped.
The server-side pass needs the live API server because that is the only
place the real CRD schemas and the cert-manager / Traefik admission
webhooks exist. It is scoped to services carrying a k8s/active marker,
since dry-run needs the target namespace to exist. userbot/ is excluded
from shellcheck: it is a git subtree, and linting upstream's scripts would
let a routine subtree pull turn the deploy gate red on code we do not own.
kubeconform, shellcheck and actionlint are now installed from pinned
versions in tool-versions.env rather than picked up from the runner's
PATH. The Compose helper is shared with the deploy workflow so both
check the same file set the same way.
forust