feat: 支持 Windows x86_64 平台编译

- 新增 WinTun TUN 设备实现(tun_windows.go),无需安装驱动,
  wintun.dll 嵌入 exe 运行时自动释放
- 新增 Windows 路由管理(route_windows.go),使用 route/netsh 命令
- 新增 Windows 路径(paths_windows.go),使用 %APPDATA%/%LOCALAPPDATA%
- 拆分 daemon 启动逻辑:launch_unix.go(Setsid) / launch_windows.go
  (CREATE_NEW_PROCESS_GROUP),公共代码提取到 launch_common.go
- 拆分提权逻辑:elevation_darwin.go(osascript) / elevation_windows.go
  (ShellExecute UAC) / elevation_other.go(pkexec)
- IPCSocketPath 按平台分散,Windows 用 %TEMP%\lmvpn.sock
- daemon 二进制名用编译时常量(daemonBinaryName),按平台选定 .exe 后缀
- Makefile 新增 build-windows 目标
- 重新标记 !darwin 文件为 !darwin && !windows

internal/tun/tun_windows.go

@@ -0,0 +1,153 @@
+//go:build windows
+
+// Package tun — Windows implementation using WinTun.
+//
+// WinTun is a userspace TUN driver for Windows developed by the
+// WireGuard project. It requires only a single wintun.dll (MIT
+// licensed) placed next to the executable — no driver installation
+// is needed.
+//
+// The DLL is embedded at compile time via //go:embed and extracted
+// to the executable's directory on first use.
+package tun
+
+import (
+	_ "embed"
+	"fmt"
+	"net"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+
+	"golang.org/x/sys/windows"
+	"golang.zx2c4.com/wintun"
+)
+
+//go:embed wintun.dll
+var wintunDLL []byte
+
+type wintunDevice struct {
+	adapter  *wintun.Adapter
+	session  wintun.Session
+	readWait windows.Handle
+	name     string
+}
+
+func createTUN(name string) (Device, error) {
+	if err := ensureWintunDLL(); err != nil {
+		return nil, fmt.Errorf("extract wintun.dll: %w", err)
+	}
+	if name == "" {
+		name = "LMVPN"
+	}
+	adapter, err := wintun.CreateAdapter(name, "Wintun", nil)
+	if err != nil {
+		return nil, fmt.Errorf("create wintun adapter: %w", err)
+	}
+	session, err := adapter.StartSession(0x800000) // 8 MiB ring
+	if err != nil {
+		adapter.Close()
+		return nil, fmt.Errorf("start wintun session: %w", err)
+	}
+	return &wintunDevice{
+		adapter:  adapter,
+		session:  session,
+		readWait: session.ReadWaitEvent(),
+		name:     name,
+	}, nil
+}
+
+func (d *wintunDevice) Name() string                { return d.name }
+func (d *wintunDevice) Close() error                { d.session.End(); return d.adapter.Close() }
+
+func (d *wintunDevice) Read(p []byte) (int, error) {
+	for {
+		packet, err := d.session.ReceivePacket()
+		if err == nil {
+			n := copy(p, packet)
+			d.session.ReleaseReceivePacket(packet)
+			return n, nil
+		}
+		if err == windows.ERROR_NO_MORE_ITEMS {
+			windows.WaitForSingleObject(d.readWait, windows.INFINITE)
+			continue
+		}
+		if err == windows.ERROR_HANDLE_EOF {
+			return 0, fmt.Errorf("wintun closed")
+		}
+		return 0, fmt.Errorf("wintun read: %w", err)
+	}
+}
+
+func (d *wintunDevice) Write(p []byte) (int, error) {
+	buf, err := d.session.AllocateSendPacket(len(p))
+	if err != nil {
+		if err == windows.ERROR_HANDLE_EOF {
+			return 0, fmt.Errorf("wintun closed")
+		}
+		return 0, fmt.Errorf("wintun allocate: %w", err)
+	}
+	copy(buf, p)
+	d.session.SendPacket(buf)
+	return len(p), nil
+}
+
+func (d *wintunDevice) Configure(localIP net.IP, prefix int, peerIP net.IP) error {
+	if localIP == nil {
+		return execCmd("netsh", "interface", "ip", "set", "address", "name="+d.name, "source=dhcp")
+	}
+	if localIP.To4() == nil {
+		return d.configureIPv6Addr(localIP, prefix)
+	}
+	mask := net.IP(net.CIDRMask(prefix, 32))
+	return execCmd("netsh", "interface", "ip", "set", "address",
+		"name="+d.name, "source=static",
+		"addr="+localIP.String(), "mask="+mask.String())
+}
+
+func (d *wintunDevice) ConfigureIPv6(localIP6 net.IP, prefix6 int) error {
+	if localIP6 == nil {
+		return nil
+	}
+	return d.configureIPv6Addr(localIP6, prefix6)
+}
+
+func (d *wintunDevice) configureIPv6Addr(ip net.IP, prefix int) error {
+	addr := fmt.Sprintf("%s/%d", ip.String(), prefix)
+	return execCmd("netsh", "interface", "ipv6", "add", "address",
+		"name="+d.name, "address="+addr)
+}
+
+func (d *wintunDevice) SetMTU(mtu int) error {
+	return execCmd("netsh", "interface", "ipv4", "set", "subinterface",
+		"name="+d.name, fmt.Sprintf("mtu=%d", mtu))
+}
+
+// ensureWintunDLL extracts the embedded wintun.dll to the executable's
+// directory if it does not already exist. The wintun Go package loads
+// the DLL via LoadLibrary which searches the exe's directory first.
+func ensureWintunDLL() error {
+	exe, err := os.Executable()
+	if err != nil {
+		return err
+	}
+	path := filepath.Join(filepath.Dir(exe), "wintun.dll")
+	if _, err := os.Stat(path); err == nil {
+		return nil
+	}
+	return os.WriteFile(path, wintunDLL, 0o644)
+}
+
+// execCmd runs a command, forwarding stdout/stderr.
+func execCmd(name string, arg ...string) error {
+	cmd := exec.Command(name, arg...)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	if err := cmd.Run(); err != nil {
+		return fmt.Errorf("%s %s: %w", name, strings.Join(arg, " "), err)
+	}
+	return nil
+}
+
+