ci: migrate npm publish authentication to OIDC and configure Node.js environment for publishing.

.github/workflows/publish.yml

@@ -7,6 +7,10 @@ on:
       - "src/**"
       - "package.json"
 
+permissions:
+  id-token: write   # ← Required for OIDC
+  contents: read
+
 jobs:
   publish:
     runs-on: ubuntu-latest
@@ -17,16 +21,19 @@ jobs:
         with:
           bun-version: latest
 
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          registry-url: 'https://registry.npmjs.org'
+
+      - name: Ensure latest npm
+        run: npm install -g npm@latest
+
       - name: Install dependencies
         run: bun install
 
       - name: Build
         run: bun run build
 
-      - name: Setup npm auth
-        run: echo "//registry.npmjs.org/:_authToken=${{ secrets.NPM_TOKEN }}" > ~/.npmrc
-
       - name: Publish
-        run: npm publish --access public
-        env:
-          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}
+        run: npm publish --access public