Move scroll publishing into push script

[MarcStdt]

Summary

• make scripts/push.sh the single release, local, and PR publishing entrypoint
• keep the catalog as explicit push lines that are easy to read and extend
• add env configuration for registry host, namespace, runtime namespace, credentials, dry-run, category/artifact toggles, and tag suffixes
• use SCROLL_TAG_SUFFIX=-pr in PR CI instead of a separate push-pr script
• move the release scroll catalog out of the GitHub Actions workflow
• validate the push script instead of the release workflow

Tests

• bash -n scripts/push.sh scripts/validate_all_scrolls.sh
• GOCACHE=/tmp/druid-local-go-cache go test ./scripts/validate-release-workflow
• GOCACHE=/tmp/druid-local-go-cache ./scripts/validate_all_scrolls.sh
• SCROLL_PUSH_DRY_RUN=1 SCROLL_REGISTRY_HOST=http://druid-gs:8088 SCROLL_REGISTRY_NAMESPACE=druid-team-experimental SCROLL_REGISTRY_RUNTIME_NAMESPACE=druid-team SCROLL_TAG_SUFFIX=-pr123 SCROLL_PUSH_CATEGORIES=0 DRUID_BIN=/tmp/druid ./scripts/push.sh | wc -l

[druid-infra]

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