feat(dll): 自 go-hua 迁入 Windows 系统 API 封装

- 互斥体防多开/ShellExecute/窗口类名与标题查询/顶层窗口目录, 新增依赖 lxn/win
- 仅 Windows, 附测试、examples/dll 例程与包 README

dll/execute.go

@@ -0,0 +1,21 @@
+// Package dll 封装 Windows 系统 API（互斥体防多开、ShellExecute、窗口操作等）。
+package dll
+
+import (
+	"github.com/lxn/win"
+	"syscall"
+)
+
+// ShellExecute 调用系统 ShellExecute 打开文件/网页/程序
+// dir 工作目录；file 目标（文件路径、URL 或程序）；args 启动参数；hide 是否隐藏窗口
+func ShellExecute(dir string, file string, args string, hide bool) bool {
+	lpOperation, _ := syscall.UTF16PtrFromString("open")
+	lpFile, _ := syscall.UTF16PtrFromString(file)
+	lpCwd, _ := syscall.UTF16PtrFromString(dir)
+	lpArgs, _ := syscall.UTF16PtrFromString(args)
+	showCmd := win.SW_SHOWNORMAL
+	if hide {
+		showCmd = win.SW_HIDE
+	}
+	return win.ShellExecute(0, lpOperation, lpFile, lpArgs, lpCwd, showCmd)
+}