feat(03-01): extend TrafficClass to 14 classes with hash-bucketed unknowns

- Replace ClassUnknown with ClassUnknown1-4 (unknown-1 through unknown-4)
- AllClasses() now returns 14 elements
- Add hashBucket() function routing unrecognized traffic deterministically
- Update synth/config.go: NumLayers=14, 4 dissonant unknown tone configs at 862-1047 Hz
- Add TestAllClassesCount and TestHashBucketDistribution tests
- Add TestClassFreqConfigsComplete and TestNumLayersMatchesAllClasses to config_test.go
- Update TestNewBankHas14Layers, TestMixerNoClip for 14 classes
- All classify and synth tests pass

classify/types.go

@@ -14,14 +14,19 @@ const (
 	ClassDHCP     TrafficClass = "DHCP"
 	ClassOtherTCP TrafficClass = "other-TCP"
 	ClassOtherUDP TrafficClass = "other-UDP"
-	ClassUnknown  TrafficClass = "unknown"
+	// D-04: ClassUnknown replaced by 4 hash-bucketed classes for distinct tones
+	ClassUnknown1 TrafficClass = "unknown-1"
+	ClassUnknown2 TrafficClass = "unknown-2"
+	ClassUnknown3 TrafficClass = "unknown-3"
+	ClassUnknown4 TrafficClass = "unknown-4"
 )
 
 // AllClasses returns all known traffic classes in display order.
 func AllClasses() []TrafficClass {
 	return []TrafficClass{
 		ClassICMP, ClassDNS, ClassHTTPS, ClassHTTP, ClassSSH,
-		ClassSMTP, ClassNTP, ClassDHCP, ClassOtherTCP, ClassOtherUDP, ClassUnknown,
+		ClassSMTP, ClassNTP, ClassDHCP, ClassOtherTCP, ClassOtherUDP,
+		ClassUnknown1, ClassUnknown2, ClassUnknown3, ClassUnknown4,
 	}
 }