enhance npm publish workflow to check for existing package version before publishing

.github/workflows/npm-publish.yml

@@ -4,6 +4,8 @@
 name: NPM Package Publish
 
 on:
+  push:
+    branches: [main]
   release:
     types: [created]
   workflow_dispatch:
@@ -31,6 +33,20 @@ jobs:
         with:
           node-version: 22
           registry-url: https://registry.npmjs.org/
-      - run: npm publish --provenance --access public
+      - run: |
+          PACKAGE_NAME=$(jq -r '.name' package.json)
+          PACKAGE_VERSION=$(jq -r '.version' package.json)
+
+          # Get the version from npm registry
+          REGISTRY_VERSION=$(npm show "$PACKAGE_NAME" version)
+
+          # Compare versions
+          if [ "$PACKAGE_VERSION" == "$REGISTRY_VERSION" ]; then
+            echo "Version $PACKAGE_VERSION already exists in the npm registry."
+            exit 0
+          else
+            echo "Version $PACKAGE_VERSION does not exist in the npm registry. Proceeding..."
+            npm publish --provenance --access public
+          fi
         env:
           NODE_AUTH_TOKEN: ${{secrets.NPM_TOKEN}}