Restructure script to use a publish_to_registry function that accepts registry, repo, and tag as parameters. Add command-line options to publish selectively: Usage: bin/publish.sh # Publish to both registries (default) bin/publish.sh --docker # Publish only to Docker Hub bin/publish.sh --github # Publish only to GitHub Container Registry bin/publish.sh v1.0.0 # Publish specific tag to both This allows local testing against a single registry without needing credentials for both. CI workflow continues to publish to both.