add build script

package.json

@@ -7,6 +7,7 @@
   },
   "license": "LicenseRef-LICENSE.md",
   "scripts": {
+    "build": "webpack --mode production",
     "start": "webpack-dev-server --open --env.server=$BUBBLE_API",
     "dev": "webpack-dev-server --open --env.server=$MY_BUBBLE_API"
   },