정적 파일들 서버에 추가

 const fs = require('fs');
 const path = require('path');
+const express = require('express');
 const app = require('./server');
 
 fs.readdirSync(path.resolve(__dirname, 'routes')).forEach((name) => {
     require(path.resolve(__dirname, 'routes', name));
 });
 
+app.use(express.static(path.resolve(__dirname, 'public')));
+
 app.listen(3429);