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/iup_export.h

@@ -0,0 +1,83 @@
+#ifndef __IUP_EXPORT_H
+#define __IUP_EXPORT_H
+
+#ifndef DOXYGEN_SHOULD_IGNORE_THIS
+/** @cond DOXYGEN_SHOULD_IGNORE_THIS */
+
+/* Mark the official functions */
+#ifndef IUP_API
+#ifdef IUP_BUILD_LIBRARY
+  #ifdef __EMSCRIPTEN__
+    #include <emscripten.h>
+    #define IUP_API EMSCRIPTEN_KEEPALIVE
+  #elif WIN32
+    #define IUP_API __declspec(dllexport)
+  #elif defined(__GNUC__) && __GNUC__ >= 4
+    #define IUP_API __attribute__ ((visibility("default")))
+  #else
+    #define IUP_API
+  #endif
+#else
+  #define IUP_API
+#endif /* IUP_BUILD_LIBRARY */
+#endif /* IUP_API */
+
+/* Mark the internal SDK functions (some not official but need to be exported) */
+#ifndef IUP_SDK_API
+#ifdef IUP_BUILD_LIBRARY
+  #ifdef __EMSCRIPTEN__
+    #include <emscripten.h>
+    #define IUP_SDK_API EMSCRIPTEN_KEEPALIVE
+  #elif WIN32
+    #define IUP_SDK_API __declspec(dllexport)
+  #elif defined(__GNUC__) && __GNUC__ >= 4
+    #define IUP_SDK_API __attribute__ ((visibility("default")))
+  #else
+    #define IUP_SDK_API
+  #endif
+#else
+  #define IUP_SDK_API
+#endif /* IUP_BUILD_LIBRARY */
+#endif /* IUP_SDK_API */
+
+/* Mark the driver functions that need to be exported */
+#ifndef IUP_DRV_API
+#ifdef IUP_BUILD_LIBRARY
+#ifdef __EMSCRIPTEN__
+#include <emscripten.h>
+#define IUP_DRV_API EMSCRIPTEN_KEEPALIVE
+#elif WIN32
+#define IUP_DRV_API __declspec(dllexport)
+#elif defined(__GNUC__) && __GNUC__ >= 4
+#define IUP_DRV_API __attribute__ ((visibility("default")))
+#else
+#define IUP_DRV_API
+#endif
+#else
+#define IUP_DRV_API
+#endif /* IUP_BUILD_LIBRARY */
+#endif /* IUP_DRV_API */
+
+/* Mark the IupImageLib function, it does not have a header of its own */
+#ifndef IUPIMGLIB_API
+#ifdef IUPIMGLIB_BUILD_LIBRARY
+  #ifdef __EMSCRIPTEN__
+    #include <emscripten.h>
+    #define IUPIMGLIB_API EMSCRIPTEN_KEEPALIVE
+  #elif WIN32
+    #define IUPIMGLIB_API __declspec(dllexport)
+  #elif defined(__GNUC__) && __GNUC__ >= 4
+    #define IUPIMGLIB_API __attribute__ ((visibility("default")))
+  #else
+    #define IUPIMGLIB_API
+  #endif
+#else
+  #define IUPIMGLIB_API
+#endif /* IUPIMGLIB_BUILD_LIBRARY */
+#endif /* IUPIMGLIB_API */
+
+/** @endcond DOXYGEN_SHOULD_IGNORE_THIS */
+#endif /* DOXYGEN_SHOULD_IGNORE_THIS */
+
+
+#endif /* __IUP_EXPORT_H */