Move publish step to sh file

.github/workflows/build_steps.sh

@@ -230,6 +230,25 @@ build_test_wasm() {
     npm run test --prefix ./wasm
 }
 
+package_wasm() {
+    mkdir -p wasm/dist
+    cp wasm/package.npm.json wasm/dist/package.json
+    cp wasm/README.md wasm/dist/README.md || true
+
+    VERSION=${GITHUB_REF#refs/tags/}
+    npm --prefix wasm/dist version "${VERSION}" --no-git-tag-version
+
+    if [ -z "${NPM_TOKEN}" ]; then
+        echo "NPM_TOKEN is not set or is invalid; aborting publish"
+        exit 1
+    fi
+    echo "//registry.npmjs.org/:_authToken=${NPM_TOKEN}" > ~/.npmrc
+
+    npm pack --dry-run ./wasm/dist
+
+    npm publish ./wasm/dist --access public
+}
+
 
 package_mjx() {
     echo "Packaging MJX..."