ci: add npm publish workflow triggered on push to main

Co-authored-by: Cursor <cursoragent@cursor.com>

.github/workflows/publish.yml

@@ -0,0 +1,44 @@
+name: Publish to npm
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    concurrency:
+      group: npm-publish
+      cancel-in-progress: false
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 18
+          registry-url: https://registry.npmjs.org/
+
+      - name: Install dependencies
+        run: npm ci --ignore-scripts
+
+      - name: Build
+        run: npm run build
+
+      - name: Check version is not already published
+        run: |
+          PKG_VERSION=$(node -p "require('./package.json').version")
+          NPM_VERSION=$(npm view react-native-mask-segment-canvas version 2>/dev/null || echo "0.0.0")
+          if [ "$PKG_VERSION" = "$NPM_VERSION" ]; then
+            echo "Error: version $PKG_VERSION already exists on npm. Please bump the version in package.json."
+            exit 1
+          fi
+          echo "Publishing version $PKG_VERSION (npm latest: $NPM_VERSION)"
+
+      - name: Publish to npm
+        run: npm publish --access public
+        env:
+          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}