Pin publish workflow npm upgrade to Node 20-compatible range

[Copilot]

The publish Actions job failed because npm@latest now resolves to npm 12, which does not support the workflow’s Node 20 runtime. This updates the workflow to keep npm in the intended modern range without crossing the Node compatibility boundary.

• Root cause addressed

  • Replace floating npm@latest with a Node 20-compatible npm range.

• Workflow change

  • In .github/workflows/publish.yml, update the npm upgrade step to install npm 11.5.1+ within major 11.

# Ensure npm 11.5.1 or later is installed (Node 20 compatible)
- name: Update npm
  run: npm install -g npm@^11.5.1

• Effect
  • Preserves the publish job’s Node 20 toolchain while preventing future breakage from npm major-version drift.