Steps to confirm the build output — no code file needed for this one

1. With the products/[id].astro route from Challenge 1 in place
   (declaring IDs 101, 102, and 103 only), run:

     npm run build

2. Inspect the generated dist/ folder:

     dist/products/101/index.html
     dist/products/102/index.html
     dist/products/103/index.html

   Exactly three files exist — one per path declared in
   getStaticPaths(). There is no dist/products/104/ folder at all.

3. If you run `npm run preview` and visit /products/104 directly,
   the server returns a genuine 404 — not a fallback render, not a
   lazily-resolved page. The route simply doesn't exist as far as
   the built site is concerned.

Notes:
- This is the concrete, observable proof of the chapter's own
  central finding: in Astro's default static output mode, a dynamic
  route only exists for the exact set of values getStaticPaths()
  returned at build time. Nothing is resolved on demand.
- Chapter 10's server output mode changes this completely — a
  dynamic route resolves per-request instead, and getStaticPaths()
  is no longer required at all.