image ingestion pipeline examples

Two paths are shown here, more as a demo than anything else.

1. ingest.sh is a simple shell script that runs as acceptance criteria checks to pull from one source (Chainguard registry), run the checks above, then push to another (any OCI compliant registry)
2. .github/workflows/ingest.yaml is the same workflow and checks, but run within GitHub Actions to show a demo of it working in a CI pipeline.