fix(publicip): rework run loop and fix restarts

- Clearing IP data on VPN disconnection clears file
- More efficient partial updates
- Fix loop exit
- Validate settings before updating

internal/publicip/interfaces.go

@@ -11,3 +11,9 @@ type Fetcher interface {
 	FetchInfo(ctx context.Context, ip netip.Addr) (
 		result ipinfo.Response, err error)
 }
+
+type Logger interface {
+	Info(s string)
+	Warn(s string)
+	Error(s string)
+}