chore: 初始化项目基础文件

src/Core/TakeoutSaaS.Shared.Abstractions/Constants/ErrorCodes.cs

@@ -0,0 +1,19 @@
+namespace TakeoutSaaS.Shared.Abstractions.Constants;
+
+/// <summary>
+/// 统一错误码常量。
+/// </summary>
+public static class ErrorCodes
+{
+    public const int BadRequest = 400;
+    public const int Unauthorized = 401;
+    public const int Forbidden = 403;
+    public const int NotFound = 404;
+    public const int Conflict = 409;
+    public const int ValidationFailed = 422;
+    public const int InternalServerError = 500;
+
+    // 业务自定义区间（10000+）
+    public const int BusinessError = 10001;
+}
+