Exercise 1: The Minimal Server — Possible Solution
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// server.js
const express = require('express');
const app = express();

app.get('/', (req, res) => {
  res.send('Hello World');
});

app.listen(3000, () => {
  console.log('Server running on http://localhost:3000');
});

CONFIRMATION
------------------------------
Running node server.js and visiting http://localhost:3000 in a
browser displays the plain text "Hello World" - confirming the
server starts correctly and a single hand-registered route responds.

WHY THIS WORKS AS AN ANSWER
------------------------------
It correctly scaffolds a minimal working Express server with one
route, and correctly confirms it responds at the expected local URL.