fix(ci): keep releases on GitHub-hosted runners

[osolmaz]

Summary

• keep the release workflow on ubuntu-latest and add an explicit warning comment not to move it back to self-hosted runners
• fix package.json repository metadata so npm no longer auto-corrects it during publish

Why

The failing run at https://github.com/openclaw/acpx/actions/runs/22893656912/job/66422303505 failed during npm publish with:

Unsupported GitHub Actions runner environment: "self-hosted". Only "github-hosted" runners are supported when publishing with provenance.

Verification

• pnpm run format:check
• npm publish --dry-run
  • publish warning about repository.url is gone
  • the remaining failure is only the expected version collision for already-published 0.1.0