feat: 实现 Java 完整解析器和不可转换语法处理 (Task 2.2, 2.8)

Task 2.2 - Java 完整解析器:
- JavaParser: 支持包声明、导入语句、类/接口/枚举提取
- 提取方法、字段、构造函数、参数
- 提取单行/多行注释和 JavaDoc 文档
- 10 个单元测试全部通过

Task 2.8 - 不可转换语法处理:
- UnconvertibleSyntaxHandler: 检测 C# 特有语法
- 支持检测：async/await, LINQ, dynamic, var, yield, record 等
- 检测模式：空条件运算符.?，空合并??, 字符串插值$等
- 转换可行性评估：置信度评分和努力程度估算
- 自动生成 TODO 注释标记
- 3 个单元测试通过

Task 4.2 - API 认证:
- AuthController: JWT 认证端点 (login, refresh, me)
- Program.cs: JWT Bearer 认证配置
- Swagger 集成认证支持

总计：39 个测试全部通过 ✅
Co-authored-by: monkeycode-ai <monkeycode-ai@chaitin.com>

CodePlay.WebAPI/Program.cs

@@ -0,0 +1,43 @@
+using System.Text;
+using Microsoft.AspNetCore.Authentication.JwtBearer;
+using Microsoft.IdentityModel.Tokens;
+
+var builder = WebApplication.CreateBuilder(args);
+
+builder.Services.AddControllers();
+builder.Services.AddEndpointsApiExplorer();
+builder.Services.AddSwaggerGen();
+
+var key = Encoding.UTF8.GetBytes("YourSuperSecretKeyThatIsAtLeast32CharactersLong");
+
+builder.Services.AddAuthentication(options =>
+{
+    options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
+    options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
+})
+.AddJwtBearer(options =>
+{
+    options.RequireHttpsMetadata = false;
+    options.SaveToken = true;
+    options.TokenValidationParameters = new TokenValidationParameters
+    {
+        ValidateIssuerSigningKey = true,
+        IssuerSigningKey = new SymmetricSecurityKey(key),
+        ValidateIssuer = false,
+        ValidateAudience = false,
+        ValidateLifetime = true
+    };
+});
+
+builder.Services.AddAuthorization();
+builder.Services.AddCors(o => o.AddPolicy("AllowAll", p => p.AllowAnyOrigin().AllowAnyMethod().AllowAnyHeader()));
+
+var app = builder.Build();
+
+app.UseSwagger();
+app.UseSwaggerUI();
+app.UseCors("AllowAll");
+app.UseAuthentication();
+app.UseAuthorization();
+app.MapControllers();
+app.Run();