Add `ah lint` GitHub Actions workflow for ArtifactHub validation

[vdemeester]

What

Add a GitHub Actions workflow that runs ah lint on PRs to validate ArtifactHub metadata before merge.

Why

We publish packages to ArtifactHub (tasks and stepactions each as separate AH repositories). The ah CLI tool can catch metadata issues (missing annotations, invalid artifacthub-repo.yaml, etc.) early in CI rather than discovering them after indexing.

How

Add a workflow (e.g. .github/workflows/artifacthub-lint.yaml) using the artifacthub/ah container image:

name: ArtifactHub Lint
on:
  pull_request:
    branches: [main]

jobs:
  ah-lint-tasks:
    runs-on: ubuntu-latest
    container:
      image: artifacthub/ah
      options: --user root
    steps:
      - uses: actions/checkout@v5
      - name: Lint tasks
        run: ah lint -k tekton-task -p task
  ah-lint-stepactions:
    runs-on: ubuntu-latest
    container:
      image: artifacthub/ah
      options: --user root
    steps:
      - uses: actions/checkout@v5
      - name: Lint stepactions
        run: ah lint -k tekton-task -p stepaction

The exact kind flags and paths may need adjustment — check ah lint --help for Tekton-specific options.

References

• ArtifactHub CLI docs
• AH's own CI using ah lint