DNS resolution, abstracted across runtimes.
Exposed as the optional IRuntimeServices.dns. fetch cannot
express an SRV lookup, which is how Consul DNS, Kubernetes headless
services, and ECS Service Connect are actually consumed — hence a resolver
seam rather than making callers reach for a runtime global.
resolveSrv(hostname: string): Promise<readonly SrvRecord[]>
Resolves SRV records for a hostname.
resolveHost(hostname: string): Promise<readonly string[]>
Resolves a hostname to IP address literals.
Concatenates A and AAAA results. A host with only one family present
resolves successfully with just that family's addresses; the lookup
rejects only when both families fail.