ci: add publish-on-tag workflow

.github/workflows/publish.yml

@@ -0,0 +1,49 @@
+name: Publish to npm
+
+on:
+  push:
+    tags: ['v*']
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+      - uses: actions/setup-node@v5
+        with:
+          node-version: '22'
+          cache: npm
+      - run: npm ci
+      - run: npm run lint
+      - run: npm test
+
+  publish:
+    needs: test
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      id-token: write
+    steps:
+      - uses: actions/checkout@v5
+      - uses: actions/setup-node@v5
+        with:
+          node-version: '22'
+          cache: npm
+          registry-url: 'https://registry.npmjs.org'
+      - run: npm ci
+      - name: Verify tag matches package.json version
+        env:
+          TAG_REF: ${{ github.ref_name }}
+        run: |
+          TAG_VERSION="${TAG_REF#v}"
+          PKG_VERSION=$(node -p "require('./package.json').version")
+          if [ "$TAG_VERSION" != "$PKG_VERSION" ]; then
+            echo "Tag $TAG_VERSION does not match package.json version $PKG_VERSION"
+            exit 1
+          fi
+      - run: npm publish --provenance --access public
+      - name: Create GitHub release
+        env:
+          GH_TOKEN: ${{ github.token }}
+          TAG_REF: ${{ github.ref_name }}
+        run: gh release create "$TAG_REF" --generate-notes