feat: initial Go/JS/Rust Origin check-in client SDKs

Standalone clients that resolve a machine unique ID (OS machine ID first,
falling back to a generated UUID persisted to disk), detect hostname/IP/
container/orchestrator, and register+re-ping origin.warky.dev's public
service-checkin endpoint on a daily interval. Ported from icy2's internal
origincheckin package but extended to the full check-in contract and made
dependency-light for external reuse.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

go/hostinfo.go

@@ -0,0 +1,100 @@
+package originclient
+
+import (
+	"net"
+	"os"
+	"strings"
+)
+
+// Hostname returns the OS hostname, or "" if it cannot be determined.
+func Hostname() string {
+	h, err := os.Hostname()
+	if err != nil {
+		return ""
+	}
+	return h
+}
+
+// OutboundIP returns the first non-loopback IPv4 address bound to this
+// host. It is a LAN-facing address, not the host's public internet
+// address, and is not part of Origin's wire contract — it exists so
+// callers can populate BaseURL/InternalURL/Description themselves.
+func OutboundIP() string {
+	addrs, err := net.InterfaceAddrs()
+	if err != nil {
+		return ""
+	}
+	for _, addr := range addrs {
+		ipNet, ok := addr.(*net.IPNet)
+		if !ok || ipNet.IP.IsLoopback() {
+			continue
+		}
+		if ip4 := ipNet.IP.To4(); ip4 != nil {
+			return ip4.String()
+		}
+	}
+	return ""
+}
+
+// ContainerID best-effort detects the Docker/Kubernetes container ID this
+// process runs in. It returns "" outside a container or when detection
+// fails; an empty container ID is treated as "not containerized" rather
+// than an error.
+func ContainerID() string {
+	if data, err := os.ReadFile("/proc/self/cgroup"); err == nil {
+		if id := parseCgroupContainerID(data); id != "" {
+			return id
+		}
+	}
+	if _, err := os.Stat("/.dockerenv"); err == nil {
+		if h := Hostname(); isContainerIDLike(h) {
+			return h
+		}
+	}
+	return ""
+}
+
+// Orchestrator best-effort detects the orchestration environment:
+// "kubernetes" under Kubernetes, "docker" in a plain Docker container, ""
+// otherwise.
+func Orchestrator() string {
+	if os.Getenv("KUBERNETES_SERVICE_HOST") != "" {
+		return "kubernetes"
+	}
+	if _, err := os.Stat("/.dockerenv"); err == nil {
+		return "docker"
+	}
+	return ""
+}
+
+// parseCgroupContainerID extracts a container ID from /proc/self/cgroup
+// content, handling both cgroup v1 (".../docker/<id>") and cgroup v2
+// systemd-scope (".../docker-<id>.scope") layouts.
+func parseCgroupContainerID(data []byte) string {
+	for _, line := range strings.Split(string(data), "\n") {
+		line = strings.TrimSpace(line)
+		idx := strings.LastIndex(line, "/")
+		if idx == -1 {
+			continue
+		}
+		segment := line[idx+1:]
+		segment = strings.TrimSuffix(segment, ".scope")
+		segment = strings.TrimPrefix(segment, "docker-")
+		if isContainerIDLike(segment) {
+			return segment
+		}
+	}
+	return ""
+}
+
+func isContainerIDLike(s string) bool {
+	if len(s) < 12 || len(s) > 64 {
+		return false
+	}
+	for _, r := range s {
+		if (r < '0' || r > '9') && (r < 'a' || r > 'f') {
+			return false
+		}
+	}
+	return true
+}