修复.NET Framework 4.8兼容性问题

- 添加必要的using引用（System, System.Windows.Forms, System.Drawing等）
- 修复Program.cs中的ApplicationConfiguration.Initialize()为.NET Framework兼容方法
- 简化System.Data.DataTable和System.Data.DataRow类型引用
- 解决Win7兼容性编译错误问题

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

WinFormsApp1/Form1.Designer.cs

@@ -1,4 +1,8 @@
-namespace WinFormsApp1
+using System;
+using System.Windows.Forms;
+using System.Drawing;
+
+namespace WinFormsApp1
 {
     partial class Form1
     {

WinFormsApp1/Form1.cs

@@ -1,3 +1,10 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Windows.Forms;
+using System.Data;
+
 namespace WinFormsApp1
 {
     public partial class Form1 : Form
@@ -97,7 +104,7 @@ namespace WinFormsApp1
             // 设置EPPlus许可证上下文
             OfficeOpenXml.ExcelPackage.LicenseContext = OfficeOpenXml.LicenseContext.NonCommercial;
 
-            var allData = new List<System.Data.DataTable>();
+            var allData = new List<DataTable>();
             var headers = new List<string>();
 
             try
@@ -121,7 +128,7 @@ namespace WinFormsApp1
                             }
 
                             var worksheet = package.Workbook.Worksheets[0]; // 使用第一个工作表
-                            var table = new System.Data.DataTable();
+                            var table = new DataTable();
 
                             // 获取表头
                             if (headers.Count == 0)
@@ -211,7 +218,7 @@ namespace WinFormsApp1
                     // 合并所有数据
                     foreach (var table in allData)
                     {
-                        foreach (System.Data.DataRow row in table.Rows)
+                        foreach (DataRow row in table.Rows)
                         {
                             for (int col = 0; col < headers.Count; col++)
                             {

WinFormsApp1/Program.cs

@@ -1,3 +1,6 @@
+using System;
+using System.Windows.Forms;
+
 namespace WinFormsApp1
 {
     internal static class Program
@@ -8,9 +11,8 @@ namespace WinFormsApp1
         [STAThread]
         static void Main()
         {
-            // To customize application configuration such as set high DPI settings or default font,
-            // see https://aka.ms/applicationconfiguration.
-            ApplicationConfiguration.Initialize();
+            Application.EnableVisualStyles();
+            Application.SetCompatibleTextRenderingDefault(false);
             Application.Run(new Form1());
         }
     }