feat: 完成 CodePlay 项目初始化和核心解析器实现

- 创建 CodePlay 解决方案和 4 个项目 (Core, Web, CLI, Tests)
- 实现核心数据模型 (ConversionRequest, ConversionResult, Project 等)
- 实现核心接口 (IParser, IConverter, ICodeGenerator 等)
- 实现基础抽象类 BaseParser
- 实现 CSharpParser 解析器 (基于 Roslyn)
- 添加 Microsoft.CodeAnalysis.CSharp NuGet 包
- 所有代码编译通过
Co-authored-by: monkeycode-ai <monkeycode-ai@chaitin.com>

CodePlay.Web/Controllers/WeatherForecastController.cs

@@ -0,0 +1,32 @@
+using Microsoft.AspNetCore.Mvc;
+
+namespace CodePlay.Web.Controllers;
+
+[ApiController]
+[Route("[controller]")]
+public class WeatherForecastController : ControllerBase
+{
+    private static readonly string[] Summaries = new[]
+    {
+        "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
+    };
+
+    private readonly ILogger<WeatherForecastController> _logger;
+
+    public WeatherForecastController(ILogger<WeatherForecastController> logger)
+    {
+        _logger = logger;
+    }
+
+    [HttpGet(Name = "GetWeatherForecast")]
+    public IEnumerable<WeatherForecast> Get()
+    {
+        return Enumerable.Range(1, 5).Select(index => new WeatherForecast
+        {
+            Date = DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
+            TemperatureC = Random.Shared.Next(-20, 55),
+            Summary = Summaries[Random.Shared.Next(Summaries.Length)]
+        })
+        .ToArray();
+    }
+}