simple-cache-api-cache-tag.js

# Cache API Docs + Example
- https://developers.cloudflare.com/workers/about/using-cache/
- https://developers.cloudflare.com/workers/reference/apis/cache

```js
addEventListener('fetch', event => {
  event.respondWith(handleRequest(event))
})

async function handleRequest(request) {
  let request = event.request
  let cache = caches.default
  let response = await cache.match(request)

  if (response) {
    return response
  }

  response = await fetch(request)

  response = new Response(response.body, response)
  response.headers.set('Cache-Tag', 'pdp')

  event.waitUntil(cache.put(request, response.clone()))
  return response
}
```