refactor: 重构项目结构，拆分回调函数并新增功能模块

- 将 callbacks.c 拆分为 cb_edit.c、cb_file.c、cb_main.c 三个模块，提高代码可维护性
- 新增 ui_utils.c 提供通用 UI 辅助函数
- 新增历史记录功能（撤销/重做）和主题切换支持
- 增加合并预览标签页，优化路径有效性检查和环境变量展开
- 更新 Makefile 以支持新的源文件结构

src/ui.c

@@ -1,6 +1,9 @@
 #include "ui.h"
 #include "globals.h"
-#include "callbacks.h"
+#include "ui_utils.h"
+#include "cb_edit.h"
+#include "cb_file.h"
+#include "cb_main.h"
 #include <stdlib.h>
 
 // 创建列表控件
@@ -8,6 +11,7 @@ Ihandle *create_path_list()
 {
     Ihandle *list = IupFlatList();
     IupSetAttribute(list, "EXPAND", "YES");
+    IupSetAttribute(list, "MULTIPLE", "YES");
     IupSetAttribute(list, "ITEMPADDING", "5x5");
     IupSetAttribute(list, "BACKCOLOR", "255 255 255");
     IupSetAttribute(list, "BORDER", "YES");
@@ -16,6 +20,7 @@ Ihandle *create_path_list()
     IupSetCallback(list, "DBLCLICK_CB", (Icallback)list_dblclick_cb);
     IupSetCallback(list, "DROPFILES_CB", (Icallback)list_dropfiles_cb);
     IupSetCallback(list, "K_ANY", (Icallback)list_k_any_cb);
+    IupSetCallback(list, "MOTION_CB", (Icallback)list_motion_cb);
     return list;
 }
 
@@ -27,6 +32,8 @@ Ihandle *create_main_buttons()
     btn_edit = IupButton("编辑(E)", NULL);
     btn_browse = IupButton("浏览(B)...", NULL);
     btn_del = IupButton("删除(D)", NULL);
+    btn_undo = IupButton("撤销(Z)", NULL);
+    btn_redo = IupButton("重做(Y)", NULL);
     btn_up = IupButton("上移(U)", NULL);
     btn_down = IupButton("下移(O)", NULL);
     btn_clean = IupButton("一键清理", NULL);
@@ -36,6 +43,8 @@ Ihandle *create_main_buttons()
     IupSetCallback(btn_edit, "ACTION", (Icallback)btn_edit_cb);
     IupSetCallback(btn_browse, "ACTION", (Icallback)btn_browse_cb);
     IupSetCallback(btn_del, "ACTION", (Icallback)btn_del_cb);
+    IupSetCallback(btn_undo, "ACTION", (Icallback)btn_undo_cb);
+    IupSetCallback(btn_redo, "ACTION", (Icallback)btn_redo_cb);
     IupSetCallback(btn_up, "ACTION", (Icallback)btn_up_cb);
     IupSetCallback(btn_down, "ACTION", (Icallback)btn_down_cb);
     IupSetCallback(btn_clean, "ACTION", (Icallback)btn_clean_cb);
@@ -45,6 +54,8 @@ Ihandle *create_main_buttons()
     IupSetAttribute(btn_edit, "RASTERSIZE", "100x32");
     IupSetAttribute(btn_browse, "RASTERSIZE", "100x32");
     IupSetAttribute(btn_del, "RASTERSIZE", "100x32");
+    IupSetAttribute(btn_undo, "RASTERSIZE", "100x32");
+    IupSetAttribute(btn_redo, "RASTERSIZE", "100x32");
     IupSetAttribute(btn_up, "RASTERSIZE", "100x32");
     IupSetAttribute(btn_down, "RASTERSIZE", "100x32");
     IupSetAttribute(btn_clean, "RASTERSIZE", "100x32");
@@ -52,36 +63,109 @@ Ihandle *create_main_buttons()
     Ihandle *vbox_btns = IupVbox(
         btn_new, btn_edit, btn_browse, btn_del,
         IupFill(), // 间隔
+        btn_undo, btn_redo,
+        IupFill(),
         btn_clean, // 放在上移下移之前，或者最下面，这里放在中间偏下
         IupFill(),
         btn_up, btn_down,
         NULL);
     IupSetAttribute(vbox_btns, "GAP", "5");
     IupSetAttribute(vbox_btns, "MARGIN", "0x0");
-    
+
     return vbox_btns;
 }
 
 // 创建底部按钮区域
 Ihandle *create_bottom_buttons()
 {
-    // 底部按钮
-    btn_ok = IupButton("确定", NULL);
-    btn_cancel = IupButton("取消", NULL);
-    btn_help = IupButton("帮助(?)", NULL);
-
-    IupSetCallback(btn_ok, "ACTION", (Icallback)btn_ok_cb);
-    IupSetCallback(btn_cancel, "ACTION", (Icallback)btn_cancel_cb);
+    // 创建底部按钮
+    btn_help = IupButton("帮助(H)", NULL);
     IupSetCallback(btn_help, "ACTION", (Icallback)btn_help_cb);
+    IupSetAttribute(btn_help, "RASTERSIZE", "80x32");
 
+    btn_theme = IupButton("深色模式", NULL);
+    IupSetCallback(btn_theme, "ACTION", (Icallback)btn_theme_cb);
+    IupSetAttribute(btn_theme, "RASTERSIZE", "80x32");
+
+    lbl_status = IupLabel("就绪");
+    IupSetAttribute(lbl_status, "EXPAND", "HORIZONTAL");
+
+    btn_import = IupButton("导入配置", NULL);
+    IupSetCallback(btn_import, "ACTION", (Icallback)btn_import_cb);
+    IupSetAttribute(btn_import, "RASTERSIZE", "100x32");
+
+    btn_export = IupButton("导出配置", NULL);
+    IupSetCallback(btn_export, "ACTION", (Icallback)btn_export_cb);
+    IupSetAttribute(btn_export, "RASTERSIZE", "100x32");
+
+    btn_ok = IupButton("确定(O)", NULL);
+    IupSetCallback(btn_ok, "ACTION", (Icallback)btn_ok_cb);
     IupSetAttribute(btn_ok, "RASTERSIZE", "100x32");
-    IupSetAttribute(btn_cancel, "RASTERSIZE", "100x32");
-    IupSetAttribute(btn_help, "RASTERSIZE", "100x32");
 
-    Ihandle *hbox_bottom = IupHbox(lbl_status, IupFill(), btn_help, btn_ok, btn_cancel, NULL);
+    btn_cancel = IupButton("取消(C)", NULL);
+    IupSetCallback(btn_cancel, "ACTION", (Icallback)btn_cancel_cb);
+    IupSetAttribute(btn_cancel, "RASTERSIZE", "100x32");
+
+    Ihandle *hbox_bottom = IupHbox(
+        btn_help,
+        btn_theme,
+        lbl_status,
+        IupFill(),
+        btn_import,
+        btn_export,
+        btn_ok,
+        btn_cancel,
+        NULL);
     IupSetAttribute(hbox_bottom, "GAP", "10");
-    IupSetAttribute(hbox_bottom, "MARGIN", "10x10");
     IupSetAttribute(hbox_bottom, "ALIGNMENT", "ACENTER");
+    IupSetAttribute(hbox_bottom, "MARGIN", "0x0");
 
     return hbox_bottom;
+}
+
+// 创建主对话框
+Ihandle *create_main_dialog()
+{
+    // 创建两个列表
+    list_sys = create_path_list();
+    list_user = create_path_list();
+    list_merged = create_path_list();
+
+    IupSetAttribute(list_merged, "READONLY", "YES");
+    IupSetAttribute(list_merged, "MULTIPLE", "NO");
+    IupSetAttribute(list_merged, "BGCOLOR", "240 240 240"); // 灰色背景
+
+    // 创建标签页
+    tabs_main = IupTabs(list_sys, list_user, list_merged, NULL);
+    IupSetAttribute(tabs_main, "TABTITLE0", "系统变量 (System PATH)");
+    IupSetAttribute(tabs_main, "TABTITLE1", "用户变量 (User PATH)");
+    IupSetAttribute(tabs_main, "TABTITLE2", "合并预览 (Merged PATH)");
+
+    // 设置标签页切换回调
+    IupSetCallback(tabs_main, "TABCHANGEPOS_CB", (Icallback)tabs_tabchange_cb);
+
+    // 搜索框
+    txt_search = IupText(NULL);
+    IupSetAttribute(txt_search, "NAME", "TXT_SEARCH");
+    IupSetAttribute(txt_search, "CUEBANNER", "搜索...");
+    IupSetCallback(txt_search, "VALUECHANGED_CB", (Icallback)txt_search_cb);
+    IupSetAttribute(txt_search, "EXPAND", "HORIZONTAL");
+
+    // 布局
+    Ihandle *btns = create_main_buttons();
+    Ihandle *hbox_mid = IupHbox(tabs_main, btns, NULL);
+    IupSetAttribute(hbox_mid, "GAP", "10");
+    IupSetAttribute(hbox_mid, "MARGIN", "0x0");
+
+    Ihandle *bottom = create_bottom_buttons();
+
+    Ihandle *vbox_main = IupVbox(txt_search, hbox_mid, bottom, NULL);
+    IupSetAttribute(vbox_main, "GAP", "10");
+    IupSetAttribute(vbox_main, "MARGIN", "10x10");
+
+    Ihandle *dlg = IupDialog(vbox_main);
+    IupSetAttribute(dlg, "TITLE", "Path Editor");
+    IupSetAttribute(dlg, "SIZE", "480x400");
+
+    return dlg;
 }