feat: Windows 安装器 + 修复 daemon 无法连接问题

- 新增 Inno Setup 安装器脚本 (installer/lmvpn.iss)，支持自定义安装路径、
  桌面快捷方式、安装前杀死旧进程，打包 wintun.dll
- Makefile 新增 installer-windows 目标，支持 ISCC 和 Wine 两种编译方式
- Windows IPC 从 AF_UNIX 改为 TCP (127.0.0.1:18923)，解决提权 daemon 与
  非提权 GUI 之间的完整性级别限制导致 daemon did not become reachable
- 修复 elevation_windows.go 中 ShellExecute 参数路径含空格时被截断的问题
  (C:\Program Files\LMVPN\lmvpnd.exe → 只取到 C:\Program)
- ensureDaemon 重试次数 40→60，添加连接失败日志便于诊断
- 新增 IPCNetwork()/IPCAddress() 跨平台函数，统一 IPC 传输层抽象

internal/ui/daemon.go

@@ -74,11 +74,14 @@ func ensureDaemon() (*ipc.Client, error) {
 
 	// Wait for the daemon to become reachable.
 	logFile := paths.DaemonLogFile()
-	for i := 0; i < 40; i++ {
+	for i := 0; i < 60; i++ {
 		time.Sleep(250 * time.Millisecond)
 		if c, err := ipc.Dial(); err == nil {
-			log.L().Info("daemon connected", "socket", paths.IPCSocketPath())
+			log.L().Info("daemon connected", "socket", paths.IPCAddress())
 			return c, nil
+		} else if i == 0 || i == 10 || i == 30 || i == 59 {
+			log.L().Warn("daemon not reachable yet, retrying",
+				"attempt", i+1, "socket", paths.IPCAddress(), "error", err)
 		}
 	}
 	return nil, fmt.Errorf("daemon did not become reachable (check %s)", logFile)

internal/ui/elevation_windows.go

@@ -15,7 +15,7 @@ const daemonBinaryName = "lmvpnd.exe"
 // launchElevated launches the daemon-launch subcommand with UAC
 // elevation via ShellExecute "runas" on Windows.
 func launchElevated(exe, daemonBin, home string, uid, gid int) error {
-	args := fmt.Sprintf("daemon-launch --user-home %s --uid %d --gid %d --daemon-bin %s",
+	args := fmt.Sprintf("daemon-launch --user-home \"%s\" --uid %d --gid %d --daemon-bin \"%s\"",
 		home, uid, gid, daemonBin)
 
 	shell32 := syscall.NewLazyDLL("shell32.dll")