Start the Go rewrite: jsjson, awg-ctrl port, differential bench

- internal/jsjson: JSON.stringify-compatible encoder and order-preserving decoder,
  tested against fixtures produced by Node itself
- internal/ctrl: awg-ctrl in Go (params, vpn:// keys, users, peers, sync, 3.1
  upgrade, CAKE shaping, metrics, monitor job, Express-compatible HTTP layer)
- internal/iauth, internal/logx: internal Ed25519 tokens and logging
- tools/diffbench: Docker bench with stubbed awg/ip/tc/nft that runs one scenario
  against the TS and Go implementations for comparison

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

internal/logx/logx.go

@@ -0,0 +1,60 @@
+// Package logx — простой логгер: человекочитаемые строки в консоль и JSON-строки в
+// файл (как winston в Node-версии: console «<ts> level: msg», файл {level,message,timestamp,…}).
+package logx
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+)
+
+type Logger struct {
+	mu   sync.Mutex
+	out  io.Writer
+	file *os.File
+}
+
+// New пишет в stdout и (если dir не пуст) в dir/app.log.
+func New(out io.Writer, dir string) *Logger {
+	l := &Logger{out: out}
+	if dir != "" {
+		if err := os.MkdirAll(dir, 0o755); err == nil {
+			if f, err := os.OpenFile(filepath.Join(dir, "app.log"), os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644); err == nil {
+				l.file = f
+			}
+		}
+	}
+	return l
+}
+
+func (l *Logger) log(level, msg string, kv []any) {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	ts := time.Now().UTC().Format("2006-01-02T15:04:05.000Z")
+	if l.out != nil {
+		fmt.Fprintf(l.out, "%s %s: %s\n", ts, level, msg)
+	}
+	if l.file != nil {
+		m := map[string]any{"level": level, "message": msg, "timestamp": ts}
+		for i := 0; i+1 < len(kv); i += 2 {
+			if k, ok := kv[i].(string); ok {
+				if e, isErr := kv[i+1].(error); isErr {
+					m[k] = e.Error()
+				} else {
+					m[k] = kv[i+1]
+				}
+			}
+		}
+		b, _ := json.Marshal(m)
+		l.file.Write(append(b, '\n'))
+	}
+}
+
+func (l *Logger) Info(msg string, kv ...any)  { l.log("info", msg, kv) }
+func (l *Logger) Warn(msg string, kv ...any)  { l.log("warn", msg, kv) }
+func (l *Logger) Error(msg string, kv ...any) { l.log("error", msg, kv) }
+func (l *Logger) Debug(msg string, kv ...any) { l.log("debug", msg, kv) }