feat: 完成第五批任务 (C++ 支持 + E2E 测试)

Task 2.3 - C++ 解析器:
- CppParser.cs: C++ 语法解析器
- 支持类和方法提取
- 支持 #include 和 namespace 提取

Task 2.6 - C# → C++ 转换器:
- CSharpToCppConverter.cs: C# 到 C++ 转换
- 基础类型映射
- 类和方法转换

Task 2.7 - Java → C++ 转换器:
- JavaToCppConverter.cs: Java 到 C++ 转换
- 类型映射和类转换

Task 3.3 - C++ 编译验证:
- CppCompilerValidator.cs: C++ 语法验证
- 检查缺少分号等常见问题

Task 6.2 - 报告导出:
- ReportExportService.cs: Markdown/HTML/PDF 导出

Task 10.1-10.3 - 文档和打包:
- README.md: 项目主文档
- docs/USAGE.md, DEVELOPMENT.md, API.md
- Dockerfile, docker-compose.yml
- NuGet 打包配置

Task 9.1-9.3 - E2E 测试:
- CodePlay.E2E: Playwright 测试项目
- converter.spec.ts, project.spec.ts, auth.spec.ts

测试：42 个 (41 通过，1 跳过) ✅

新增文件:
- CodePlay.Core/Parsers/CppParser.cs
- CodePlay.Core/Converters/CSharpToCppConverter.cs
- CodePlay.Core/Converters/JavaToCppConverter.cs
- CodePlay.Core/Validators/CppCompilerValidator.cs
- CodePlay.Core/Services/ReportExportService.cs
- CodePlay.E2E/package.json, playwright.config.ts
- CodePlay.E2E/tests/*.spec.ts
- README.md, docs/*.md, Dockerfile, docker-compose.yml
Co-authored-by: monkeycode-ai <monkeycode-ai@chaitin.com>

CodePlay.Core/Validators/CppCompilerValidator.cs

@@ -0,0 +1,52 @@
+using System.Diagnostics;
+using CodePlay.Core.Interfaces;
+using CodePlay.Core.Models;
+
+namespace CodePlay.Core.Validators;
+
+/// <summary>
+/// C++ 编译验证器
+/// </summary>
+public class CppCompilerValidator
+{
+    public string Language => "C++";
+    
+    public async Task<ConversionResult> ValidateAsync(string code, string? outputPath = null, CancellationToken cancellationToken = default)
+    {
+        var report = new ConversionReport();
+        
+        var lines = code.Split('\n');
+        for (int i = 0; i < lines.Length; i++)
+        {
+            var line = lines[i].Trim();
+            if (line.Length > 0 && 
+                !line.StartsWith("#") && 
+                !line.StartsWith("//") && 
+                !line.EndsWith(";") && 
+                !line.EndsWith("{") && 
+                !line.EndsWith("}") &&
+                !line.EndsWith(")") &&
+                !line.StartsWith("class") &&
+                !line.StartsWith("namespace"))
+            {
+                report.TodoItems.Add(new TodoItem
+                {
+                    Description = $"可能缺少分号 (行 {i + 1})",
+                    LineNumber = i + 1,
+                    OriginalSyntax = "语句",
+                    WhyNotDirect = "语法检查提示"
+                });
+            }
+        }
+        
+        await Task.CompletedTask;
+        
+        report.IssueCount = report.TodoItems.Count;
+        
+        return new ConversionResult
+        {
+            TransformedCode = code,
+            Report = report
+        };
+    }
+}