Add mini web demo

demo/configs/webpack/prod.js

@@ -0,0 +1,16 @@
+// production config
+const { merge } = require("webpack-merge");
+const { resolve } = require("path");
+const Dotenv = require("dotenv-webpack");
+const commonConfig = require("./common");
+
+module.exports = merge(commonConfig, {
+  mode: "production",
+  output: {
+    filename: "js/bundle.[contenthash].min.js",
+    path: resolve(__dirname, "../../dist"),
+    publicPath: "/",
+  },
+  devtool: "source-map",
+  plugins: [new Dotenv()],
+});