Design and deploy iroh-relay through edge PoPs

[zachsmith1]

Design and deploy iroh-relay to edge PoPs so clients select a nearby relay while gateways/peers can target that exact relay for consistent routing. Use PoP‑specific relay hostnames (or a discovery API) so endpoints pick a “home relay” via latency probes, and avoid anycast for gateway dialing unless you can guarantee sticky routing per connection.

• Define PoP relay inventory (hostnames, TLS, metrics, QUIC addr‑discovery) and publish a relay map for clients to probe.
• Implement/choose client discovery: DNS geo/latency routing or a small API that returns nearest relay URLs.
• Pick hostname format: https://usw1-1.relay.n0.iroh-canary.iroh.link. (iroh) so maybe something like https://relay.iroh.<location>.datumconnect.net

Ref: https://github.com/n0-computer/iroh/tree/main/iroh-relay