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

Same fix as ai-forms, before hitting the same failure. Trusted publishing
is configured per package on npmjs.com and cannot be configured for a
package that has never been published, so the token-free workflow fails
on the first release with E404 on the PUT.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: Mao Nakamoto

.github/workflows/publish.yml

@@ -38,7 +38,17 @@ jobs:
             exit 1
           fi
 
-      # No token: id-token above lets the CLI exchange a short-lived OIDC
-      # credential with npm. Provenance is generated automatically for a public
-      # package from a public repo, so --provenance is not needed either.
+      # OIDC (id-token above) is the preferred credential and needs no secret.
+      # But trusted publishing is configured per package on npmjs.com, and a
+      # package that has never been published cannot have it configured — so
+      # OIDC alone cannot do the FIRST publish. Confirmed on ai-forms: the
+      # provenance statement was signed and logged to sigstore, then the PUT
+      # returned E404 "could not be found or you do not have permission",
+      # which reads like a missing package rather than a missing credential.
+      #
+      # NPM_TOKEN covers only that first publish. Once this package exists and
+      # a trusted publisher is configured, npm prefers OIDC and the secret can
+      # be deleted.
       - run: npm publish
+        env:
+          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}