chore(chart): list the kobe Helm chart on Artifact Hub

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Now that the kobe Helm chart is published as an OCI artifact to Docker Hub (oci://registry-1.docker.io/zondax/kobe, versioned with the operator — currently 0.37.0), we can also list it on Artifact Hub for discoverability. Artifact Hub indexes the chart from the OCI registry; it does not host it.

Prerequisite: the zondax/kobe Docker Hub repo must be public, and chart tags must be valid semver (0.37.0 qualifies).

Steps (verified against the Artifact Hub docs):

1. Create / sign in to an Artifact Hub account and a zondax organization.
2. Add a repository → kind Helm, URL oci://registry-1.docker.io/zondax/kobe. Artifact Hub indexes each semver-tagged version.
3. Claim ownership + earn the Verified Publisher badge: take the repositoryID Artifact Hub generates for the repo, put it in an artifacthub-repo.yml, and push it to the OCI repo as a metadata artifact with oras:

   oras push registry-1.docker.io/zondax/kobe:artifacthub.io \
     --config /dev/null:application/vnd.cncf.artifacthub.config.v1+yaml \
     artifacthub-repo.yml:application/vnd.cncf.artifacthub.repository-metadata.layer.v1.yaml
   

4. (Optional) enrich charts/kobe/Chart.yaml with artifacthub.io/* annotations (changelog, license, maintainers, links, images, security) for a richer listing.

Notes:

• Steps 1–2 are account/UI actions; 3–4 are small repo changes plus a one-time oras push.
• OCI-hosted Helm repos on Artifact Hub can't force-reindex an existing version by digest change — a limitation, not a blocker.

Ref: https://artifacthub.io/docs/topics/repositories/helm-charts/