ax(ueps): replace abstract variable names in PacketBuilder comment with concrete values

AX Principle 2 — comments must show concrete usage with realistic values,
not abstract placeholder names. The struct-level comment for PacketBuilder
used `intentID` and `payload` (undefined in context); replaced with 0x01
and []byte("ping") so an agent reading it sees an exact working call.

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

pkg/ueps/packet.go

@@ -37,7 +37,7 @@ type UEPSHeader struct {
 	ThreatScore  uint16 // header.ThreatScore = 100 // elevated on HMAC mismatch; 0 = clean, 65535 = maximum threat
 }
 
-// builder := ueps.NewPacketBuilder(intentID, payload); frame, _ := builder.MarshalAndSign(secret)
+// builder := ueps.NewPacketBuilder(0x01, []byte("ping")); frame, _ := builder.MarshalAndSign([]byte("shared-secret"))
 type PacketBuilder struct {
 	Header  UEPSHeader
 	Payload []byte