Fail the release workflow when npm stage publish fails

[ProgramComputer]

The Release workflow's staging step piped npm stage publish into tee under GitHub's default bash -e, which has no pipefail, so a failed publish still passed the step. This sets pipefail on that step, as the workflow's other multi-line steps already do.

What happened

The v1.3.1 Release workflow ran twice. The second run (38112041476) got E409 Conflict ... Cannot stage previously published version "1.3.1" from npm, but finished green, and its "Next steps" summary said the version was staged. Nothing was changed on npm: the first run's stage was the only one, and it was the one approved.

With this change, a failed npm stage publish fails the step, and the "Next steps" summary is skipped because it only runs after the earlier steps succeed.

Other piped commands

Every other piped command in release.yml already runs under set -euo pipefail. Every step in verify-release.yml either sets shell: bash, which GitHub runs with -eo pipefail, or sets pipefail itself. ci.yml has no piped commands.

Verification

• The step's old and new forms, run under bash -e with a failing command in place of npm: the old form exits 0 and the new form exits 1. With a succeeding command, the new form exits 0.
• release.yml parses as valid YAML, and the parsed step script starts with set -euo pipefail.
• The Release workflow itself was not run, because it would stage a package.