feat(01-01): install Go 1.24, initialize module, create shared types

- Initialize Go module github.com/netsynth/netsynth with Go 1.24.1
- Create classify/types.go with 11 TrafficClass constants (ICMP, DNS, HTTPS,
  HTTP, SSH, SMTP, NTP, DHCP, other-TCP, other-UDP, unknown)
- Add ClassifiedPacket and WindowSnapshot shared types
- Add Phase 1 dependencies: gopacket v1.5.0, go-pcap, cobra v1.10.2

classify/types.go

@@ -0,0 +1,43 @@
+package classify
+
+// TrafficClass represents a classified network traffic category.
+type TrafficClass string
+
+const (
+	ClassICMP     TrafficClass = "ICMP"
+	ClassDNS      TrafficClass = "DNS"
+	ClassHTTPS    TrafficClass = "HTTPS"
+	ClassHTTP     TrafficClass = "HTTP"
+	ClassSSH      TrafficClass = "SSH"
+	ClassSMTP     TrafficClass = "SMTP"
+	ClassNTP      TrafficClass = "NTP"
+	ClassDHCP     TrafficClass = "DHCP"
+	ClassOtherTCP TrafficClass = "other-TCP"
+	ClassOtherUDP TrafficClass = "other-UDP"
+	ClassUnknown  TrafficClass = "unknown"
+)
+
+// 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,
+	}
+}
+
+// ClassifiedPacket pairs a raw packet's classification result with metadata.
+type ClassifiedPacket struct {
+	Class    TrafficClass
+	SrcPort  uint16
+	DstPort  uint16
+	Protocol string // "tcp", "udp", "icmp"
+	Length   int
+}
+
+// WindowSnapshot holds aggregated packet counts for a time window.
+// This is the contract between the aggregation stage and future audio synthesis (Phase 2).
+type WindowSnapshot struct {
+	Counts       map[TrafficClass]int64
+	TotalPackets int64
+	WindowIndex  int
+}