chore: remove eszip-viewer link and crux.land example

[piscisaureus]

• Drop the eszip-viewer.deno.dev link from the README — the
  deployment is being shut down
• Delete js/examples/worker.tsx and js/examples/build.ts, which
  imported from crux.land (also shutting down)

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}