NPM CI is failing (and we should switch to NPM trusted publisher)

[manics]

Bug description

NPM CI is currently failing:
https://github.com/jupyterhub/jupyter-server-proxy/actions/runs/19271630696/job/55101291800

> Run npm publish --dry-run ./jsdist/jupyterhub-jupyter-server-proxy-*.tgz

npm warn Unknown user config "always-auth". This will stop working in the next major version of npm.
npm error You must specify a tag using --tag when publishing a prerelease version.

To fix the CI we'll need to add a --tag.

Since we're planning a release we should also switch to an NPM trusted publisher for additional security, and because the token will be invalidated at some point:

• Replace NPM tokens with trusted publisher workflow team-compass#828
• enable trusted publishing configurable-http-proxy#610