Add dedicated GET /hello endpoint returning plain text response

[Copilot]

The issue asks for a hello response behavior. This PR adds a focused route so clients can request a deterministic plain-text "hello" payload without affecting existing endpoints.

• Route addition

  • Added GET /hello in index.js.
  • Response is plain text: hello.

• Behavioral scope

  • Existing routes (/, /silly, /silly2, /test, PATCH handler) remain unchanged.

app.get("/hello", (req, res) => {
  console.log(`${new Date()} ${req.method} ${req.path}`);
  res.send("hello");
});