ci: OIDC cannot do the first publish — keep a token for it

[catomean]

#13 removed NODE_AUTH_TOKEN in favour of OIDC trusted publishing. That is the right destination, but it cannot get us there: trusted publishing is configured per package on npmjs.com, and a package that has never been published cannot have a trusted publisher configured.

Observed on tag v0.1.1 (run 31953553423):

npm notice publish Signed provenance statement with source and build information from GitHub Actions
npm notice publish Provenance statement published to transparency log
npm error code E404
npm error 404 Not Found - PUT https://registry.npmjs.org/ai-forms
npm error 404  The requested resource 'ai-forms@0.1.1' could not be found or you do not have permission to access it.

Provenance signing succeeded — that part of OIDC works. The publish itself was unauthenticated, and npm answers 404 rather than 401 for an unauthenticated publish of a non-existent package, which reads like a missing package instead of a missing credential.

This restores NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }} on the publish step, keeping id-token: write and everything else from #13. npm prefers OIDC whenever the package has a trusted publisher, so after the first release this secret is unused and can be deleted.

🤖 Generated with Claude Code

[catomean]

Superseded by #14, which landed the same fix (token for the first publish, OIDC afterwards) while this was open. Closing as duplicate — no disagreement, just two sessions reaching it at once.