feat: 项目初始化 + 3D方块世界原型 + AI助搭系统

初始化 monorepo: Go后端(7微服务) + Unity客户端(9模块) + 启动器

HTML5原型: Three.js 3D体素世界, Perlin噪声地形, 原版材质, 22种方块

Minecraft创造模式背包: 双栏布局, 拖拽移动物品, 方向性元件引脚

AI助搭策划文档 + 客户端/服务端骨架 + Docker Compose + CI

launcher/PCL-CE/PCL.Core/Link/Scaffolding/Exceptions/FailedToGetPlayerException.cs

@@ -0,0 +1,14 @@
+using System;
+
+namespace PCL.Core.Link.Scaffolding.Exceptions;
+
+public class FailedToGetPlayerException : Exception
+{
+    public FailedToGetPlayerException() : base()
+    {
+    }
+
+    public FailedToGetPlayerException(string msg) : base(msg)
+    {
+    }
+}

launcher/PCL-CE/PCL.Core/Link/Scaffolding/Exceptions/ScaffoldingRequestException.cs

@@ -0,0 +1,35 @@
+using System;
+
+namespace PCL.Core.Link.Scaffolding.Exceptions;
+
+/// <summary>
+/// Exception thrown when a scaffolding request fails with a non-success status code.
+/// </summary>
+public class ScaffoldingRequestException(byte statusCode, string? serverMessage = null) : Exception(_BuildMessage(
+    statusCode,
+    serverMessage))
+{
+    /// <summary>
+    /// The status code returned by the scaffolding server.
+    /// </summary>
+    public byte StatusCode { get; } = statusCode;
+
+    /// <summary>
+    /// The error message or details returned by the server, if any.
+    /// </summary>
+    public string? ServerMessage { get; } = serverMessage;
+
+    private static string _BuildMessage(byte statusCode, string? serverMessage)
+    {
+        var errorType = statusCode switch
+        {
+            >= 32 and < 64 => "Protocol-defined error",
+            255 => "Unknow error",
+            _ => "Generic error"
+        };
+
+        return string.IsNullOrEmpty(serverMessage)
+            ? $"Scaffolding request failed with status code {statusCode} ({errorType})."
+            : $"Scaffolding request failed with status code {statusCode} ({errorType}): {serverMessage}";
+    }
+}