refactor(edge): unify dynamic IP detection and prioritize IPv4 reporting

- Align agent, relay, and flared to dynamically resolve IP during heartbeat using the nodeip package (when not manually configured).
- Update GeoIP outbound IP strategy to prefer IPv4 HTTP client lookup using tcp4 dialer and fall back to dual-stack tcp.
- Optimize agent profile fingerprinting to exclude dynamic UptimeSeconds and ReportedAtUnix fields, preventing redundant updates.
- Refactor unit tests to prevent outbound network queries during tests.

internal/apps/agent/observability/collector.go

@@ -148,7 +148,10 @@ func collectProfile(cfg *config.Config) *protocol.NodeSystemProfile {
 }
 
 func fingerprintProfile(profile *protocol.NodeSystemProfile) string {
-	raw, err := json.Marshal(profile)
+	cloned := *profile
+	cloned.UptimeSeconds = 0
+	cloned.ReportedAtUnix = 0
+	raw, err := json.Marshal(&cloned)
 	if err != nil {
 		return ""
 	}