Implements the full monitoring loop:
- Immediate checks on startup, then periodic DNS+port and TLS cycles
- Domain NS change detection with notifications
- Per-nameserver hostname record tracking with change/failure/recovery
and inconsistency detection
- TCP port 80/443 monitoring with state change notifications
- TLS certificate monitoring with change, expiry, and failure detection
- State persistence after each cycle
- First run establishes baseline without notifications
- Graceful shutdown via context cancellation
Defines DNSResolver, PortChecker, TLSChecker, and Notifier interfaces
for dependency injection. Updates main.go fx wiring and resolver stub
signature to match per-NS record format.
Closes#2
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.
