chore: 清理旧版IUP库文件并更新头文件路径

删除旧的iup-3.31_Win64_dllw6_lib目录下的所有DLL和静态库文件
将IUP头文件从旧目录迁移到新的libs/IUP/include统一路径
更新CMakeLists.txt中的包含路径和库链接配置
简化DLL复制逻辑，只复制核心iup.dll文件

libs/IUP/include/iupfiledlg.h

@@ -0,0 +1,24 @@
+/** \file
+ * \brief New FileDlg (Windows Only).
+ *
+ * See Copyright Notice in "iup.h"
+ */
+ 
+#ifndef __IUPFILEDLG_H 
+#define __IUPFILEDLG_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* the only exported function, 
+   once called it will replace regular IupFileDlg */
+
+int IupNewFileDlgOpen(void);
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif