Passkey relay test page

Phase 0 of docs/vibe-passkey-relay.plan.md. Works only when this page's origin () is in Chrome's WebAuthenticationRemoteDesktopAllowedOrigins policy and the Chrome profile is affiliated.

1. Self-test (phase 0a)

Signs a throwaway challenge as if this page were the site below. Register a passkey for that site first, in the provider you want to test.

Site (RP ID)

2. Sign a request from the pod (phase 0c)

Request JSON (from the relay tab's Copy request)

Response JSON (paste this into the relay tab)