ax(ueps): replace prose ThreatScore comment with usage example

AX Principle 2: comments must show usage with concrete values, not
restate what the type signature already says. All other UEPSHeader
field comments used assignment examples; ThreatScore was the outlier.

Co-Authored-By: Charon <charon@lethean.io>

pkg/ueps/packet.go

@@ -34,7 +34,7 @@ type UEPSHeader struct {
 	CurrentLayer uint8  // header.CurrentLayer = 5 // Application; 3 = Network, 4 = Transport
 	TargetLayer  uint8  // header.TargetLayer = 3 // Network; 5 = Application (loopback)
 	IntentID     uint8  // header.IntentID = 0x01 (ping), 0x02 (data), 0x03 (auth)
-	ThreatScore  uint16 // 0–65535; elevated by integrity violations
+	ThreatScore  uint16 // header.ThreatScore = 100 // elevated on HMAC mismatch; 0 = clean, 65535 = maximum threat
 }
 
 // builder := ueps.NewPacketBuilder(intentID, payload); frame, _ := builder.MarshalAndSign(secret)