Intercept and rewrite outbound API responses in a Playwright test using route.fulfill() with a custom JSON body

Verified steps

1. Set up a route before navigating: await page.route('**/api/products**', async route => { ... })
2. Inside the handler, fetch the real response if needed: const response = await route.fetch()
3. Modify the JSON body: const json = await response.json(); json.price = 0;
4. Fulfill with the modified body: await route.fulfill({ response, json })
5. Navigate to the page: await page.goto('/shop') — the intercepted response will return the modified data
6. Assert that the UI reflects the stubbed data using standard Playwright locator assertions