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/machineid.go

@@ -0,0 +1,87 @@
+package originclient
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/google/uuid"
+)
+
+// errMachineIDUnavailable is returned by the OS-specific machineID() when
+// no real machine ID could be read.
+var errMachineIDUnavailable = errors.New("originclient: OS machine id unavailable")
+
+// machineIDFunc is a variable indirection over the OS-specific machineID()
+// so tests can stub OS machine-id lookup without depending on the actual
+// host's state.
+var machineIDFunc = machineID
+
+// ResolveMachineID returns the unique install ID to report to Origin, in
+// priority order:
+//
+//  1. explicit, if non-empty — a caller-supplied override.
+//  2. the real OS machine ID (/etc/machine-id on Linux, IOPlatformUUID on
+//     macOS, MachineGuid on Windows), if readable.
+//  3. the ID already persisted at path, if present.
+//  4. a newly generated UUID, which ResolveMachineID attempts to persist to
+//     path for future runs.
+//
+// OS-ID and persistence failures are logged as warnings, not returned as
+// errors: ResolveMachineID always returns a usable ID, falling back to one
+// that only lives for this process if it cannot be read from the OS or
+// saved to disk. logger may be nil.
+func ResolveMachineID(explicit, path string, logger Logger) string {
+	if logger == nil {
+		logger = noopLogger{}
+	}
+
+	if id := strings.TrimSpace(explicit); id != "" {
+		return id
+	}
+
+	if id, err := machineIDFunc(); err == nil {
+		if id = strings.TrimSpace(id); id != "" {
+			return id
+		}
+	} else {
+		logger.Warn("machine id: OS machine id unavailable, falling back to a generated id", err)
+	}
+
+	if path == "" {
+		path = defaultInstallIDPath()
+	}
+
+	if data, err := os.ReadFile(path); err == nil {
+		if id := strings.TrimSpace(string(data)); id != "" {
+			return id
+		}
+	}
+
+	id := uuid.NewString()
+	if err := persistInstallID(path, id); err != nil {
+		logger.Warn("machine id: failed to persist generated id, using an ephemeral id for this run", err)
+	}
+	return id
+}
+
+func persistInstallID(path, id string) error {
+	if dir := filepath.Dir(path); dir != "." && dir != "" {
+		if err := os.MkdirAll(dir, 0o750); err != nil {
+			return err
+		}
+	}
+	return os.WriteFile(path, []byte(id+"\n"), 0o600)
+}
+
+// defaultInstallIDPath returns the fallback-UUID persistence path used when
+// Config.InstallIDPath is unset: the OS user-config directory, or the OS
+// temp directory if that cannot be determined.
+func defaultInstallIDPath() string {
+	dir, err := os.UserConfigDir()
+	if err != nil || dir == "" {
+		dir = os.TempDir()
+	}
+	return filepath.Join(dir, "origin-client", "install-id")
+}