Classify DNS names as apex domains or hostnames using the Public
Suffix List (golang.org/x/net/publicsuffix). Correctly handles
multi-level TLDs like .co.uk and .com.au.
Full project structure following upaas conventions: uber/fx DI, go-chi
routing, slog logging, Viper config. State persisted as JSON file with
per-nameserver record tracking for inconsistency detection. Stub
implementations for resolver, portcheck, tlscheck, and watcher.
