fix: correct web demo next config

Author: josudoey

packages/web-demo/next.config.ts

@@ -1,7 +1,11 @@
 import type { NextConfig } from "next";
 
+const isProd = process.env.NODE_ENV === "production"
+
 const nextConfig: NextConfig = {
-  output: "export"
+  output: "export",
+  basePath: isProd ? "/js-jieba" : undefined,
+  assetPrefix: isProd ? "/js-jieba/" : undefined,
 };
 
 export default nextConfig;