proposal: custom Kubernetes manifests and CRDs via .deployah/ #4

The generated chart covers common app resources. Teams still need things Deployah does not generate (NetworkPolicy, PrometheusRule, app-owned CRDs). There was no first-class place for that YAML.

Shipped in #5.

.deployah/
  manifests/          # appended to the Helm release
    common.yaml
    prod/extra.yaml   # env-scoped (prefix match)
  crds/               # applied before install/upgrade
    my-crd.yaml

Manifests load literally. No Helm templating, no env substitution. Reserved deployah.dev/* keys the user does not own are stripped. Empty namespace becomes the release namespace. Collision with a generated object fails.

CRDs wait for Established. --crds create (default) or create-replace. Never pruned on uninstall. Plan shows extras in the diff and reports pending CRDs.

deployah init scaffolds the directories. Catalog / third-party charts are #8. Kustomize patches of generated objects are #31.