Buat 4 endpoint untuk resource books:

1. GET /books, return JSON {"method": "GET"}
2. POST /books, return JSON {"method": "POST"} dengan status 201
3. PUT /books/:id, return JSON {"method": "PUT", "id": req.params.id}
4. DELETE /books/:id, return status 204 tanpa body

Hint

• Setiap HTTP method punya makna: GET=baca, POST=buat, PUT=update, DELETE=hapus.
• Return JSON response yang sesuai per method.
• GET /books → return data, POST /books → return created item.