[starter] Create a tiny, Web-1.0-style 404 Web Ring for fellowship participants

[trey-darley]

Goal

Create a tiny, Web-1.0-style 404 Web Ring for fellowship participants.

No backend. No accounts. No auth. No analytics. No SaaS.
Pure hyperlinks + a static member list.

Requirements

1) Ring snippet for participants

Participants add this to their 404 page:

<div class="pt-404-ring">
  <a href="https://404.propertools.be/ring?prev">←</a>
  <a href="https://404.propertools.be/ring">404 Ring</a>
  <a href="https://404.propertools.be/ring?next">→</a>
</div>