按照合并结果文件标准调整编码

- 优先使用UTF-8读取文件以支持德语特殊字符(Ü, ü, ö等)
- 输出文件使用UTF-8 with BOM格式保存
- 确保在Windows下能正确显示中文字符和特殊字符
- 完全按照'需求/合并结果/CH-875.txt'的格式标准

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

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

FileMerger.cs

@@ -155,15 +155,15 @@ namespace SlideCombine
             try
             {
                 string[] lines;
+                // 先尝试UTF-8，支持特殊字符如Ü、ü等
                 try
                 {
-                    // 先尝试GBK编码，因为示例文件是中文的
-                    lines = File.ReadAllLines(txtFile, Encoding.GetEncoding("GBK"));
+                    lines = File.ReadAllLines(txtFile, Encoding.UTF8);
                 }
                 catch
                 {
-                    // 如果GBK失败，再尝试UTF-8
-                    lines = File.ReadAllLines(txtFile, Encoding.UTF8);
+                    // 如果UTF-8失败，尝试GBK
+                    lines = File.ReadAllLines(txtFile, Encoding.GetEncoding("GBK"));
                 }
 
                 foreach (var line in lines)
@@ -251,16 +251,9 @@ namespace SlideCombine
                     var outputFileName = $"{result.BaseFileName}.txt";
                     var outputFilePath = Path.Combine(outputPath, outputFileName);
 
-                    // 添加BOM标记并使用ANSI编码保存
-                    var bom = Encoding.UTF8.GetPreamble();
-                    var content = Encoding.Default.GetBytes(result.OutputContent);
-
-                    using (var fs = new FileStream(outputFilePath, FileMode.Create))
-                    {
-                        // 写入UTF-8的BOM（与示例文件一致）
-                        fs.Write(bom, 0, bom.Length);
-                        fs.Write(content, 0, content.Length);
-                    }
+                    // 使用UTF-8 with BOM保存，支持特殊字符
+                    var utf8WithBom = new UTF8Encoding(true);
+                    File.WriteAllText(outputFilePath, result.OutputContent, utf8WithBom);
                 }
             }
         }