feat(skills): add rhdh-bump-yarn for multi-repo Yarn Berry bumps

[nickboldt]

Summary

• Add rhdh-bump-yarn skill + scripts/bump-yarn.js to bump Yarn Berry (binaries, yarnPath/packageManager/Containerfile pins) across rhdh-plugins, rhdh, overlays, rhdh downstream, and rhdh-plugin-catalog
• Default refreshes yarn.lock via yarn install --mode=skip-build (opt out with --no-refresh-locks)
• Document the skill in README under a new Yarn section

Test plan

• node skills/rhdh-bump-yarn/scripts/bump-yarn.js --help
• --scan --root <repo> on at least one checkout
• --dry-run --to 4.17.1 --root <repo> shows expected binaries/files
• Optional: real bump on a throwaway clone with/without --no-refresh-locks

Generated-by: cursor

Ref: https://redhat.atlassian.net/browse/RHIDP-16074

[jonkoops]

Pretty sure that most of this can be handled by running two commands:

yarn set version stable
yarn install

Basically, this just needs to run everywhere there is a package.json with a packageManager field with Yarn configured. Any agent should be clever enough to find those using some CLI-foo. No need to carry a bunch of custom JS code for it.

[nickboldt]

Good call — for normal workspaces yarn set version <exact> + lock refresh is the right API; we shouldn’t reimplement Berry binary download / packageManager+yarnPath rewrites.

Slimmed the skill/script accordingly: matching packageManager dirs now run yarn set version <to> (exact version so we stay aligned with the Renovate/reference bump, not stable). What’s left in the JS is only what Yarn can’t see across this five-repo set:

• selective --from (leave roadie/backstage/dcm / Yarn 3 alone)
• Containerfile / ENV YARN= / embedded yarn set version text
• orphan .yarn/releases (distgit) without packageManager
• Fullsend helper hardcodes (rhdh-plugins)
• inherited yarn.lock refresh (YN0028 after root-only bumps)

Happy to trim further if you think any of those extras belong in the skill doc only (agent CLI-foo) rather than the script.

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Decisions / wording here: Auto (Cursor agent router), powered by Composer.