ax(ueps): replace prose struct comment on UEPSHeader with usage example

UEPSHeader's type-level comment restated the name in prose; replaced with
a concrete struct-literal example (AX principle 2). Field inline comments
updated from vague labels to descriptive value-context notes.

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

pkg/ueps/packet.go

@@ -20,13 +20,13 @@ const (
 	TagPayload     = 0xFF // The Data
 )
 
-// UEPSHeader represents the conscious routing metadata
+// h := ueps.UEPSHeader{Version: 0x09, CurrentLayer: 5, TargetLayer: 3, IntentID: 0x01, ThreatScore: 0}
 type UEPSHeader struct {
-	Version      uint8  // Default 0x09
-	CurrentLayer uint8
-	TargetLayer  uint8
-	IntentID     uint8  // Semantic Token
-	ThreatScore  uint16 // 0-65535
+	Version      uint8  // 0x09 = IPv9
+	CurrentLayer uint8  // OSI layer of the sender (5 = Application)
+	TargetLayer  uint8  // OSI layer of the destination
+	IntentID     uint8  // semantic token identifying the packet's purpose
+	ThreatScore  uint16 // 0–65535; elevated by integrity violations
 }
 
 // builder := ueps.NewBuilder(intentID, payload); frame, _ := builder.MarshalAndSign(secret)