feat: AuthSDK 认证中心完整实现（对齐 C# AuthSDK）

- SimApiAuthClient：SimApiHttpClient 子类，凭证取 AuthCenterOptions
- SimApiAuthCenter：群组/Profile/内部应用/系统登录/安全验证 12 接口 + VerifySign
- SimApiAuthIam：注册权限/获取权限/校验权限（无权限 403）
- SimApiAuthCenterMiddleware：网关透传（三头 MD5 校验 + Base64 解码 LoginInfo）
- SimApiAuthDto：7 个 DTO（data 字段用 JsonValue 规避宏约束）

src/authsdk/SimApiAuthCenterMiddleware.cj

@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2025 SimcuTeam. All rights reserved.
+ * 移植自 C# 项目 SimApi（E:\simcu\simapi-net），遵循 MIT 许可证。
+ * AuthSDK/SimApiAuthCenterMiddleware：网关透传认证中间件。
+ */
+
+package simapi.authsdk
+
+import soulsoft_web_http.*
+import simapi.communications.*
+import simapi.configurations.*
+import simapi.helpers.*
+
+/**
+ * 网关透传认证中间件（对齐 C# SimApiAuthCenterMiddleware）：
+ * 当请求带 X-SimApi-Gate-Auth / X-SimApi-Gate-Time / X-SimApi-Gate-Sign 三头时，
+ * 校验 MD5 签名（appId=..&auth=..&time=..&appKey=..），通过则 Base64 解码登录信息写入 LoginInfo。
+ */
+public class SimApiAuthCenterMiddleware <: IMiddleware {
+    private let _options: SimApiOptions
+
+    public init(options: SimApiOptions) {
+        this._options = options
+    }
+
+    public func invoke(context: HttpContext, next: RequestDelegate): Unit {
+        let auth = context.request.headers.get("X-SimApi-Gate-Auth")
+        let time = context.request.headers.get("X-SimApi-Gate-Time")
+        let sign = context.request.headers.get("X-SimApi-Gate-Sign")
+        if (auth != None && time != None && sign != None) {
+            let authValue = auth.getOrThrow()
+            let timeValue = time.getOrThrow()
+            let signValue = sign.getOrThrow()
+            if (!authValue.isEmpty()) {
+                let authOptions = _options.simApiAuthCenterOptions
+                let signStr = "appId=${authOptions.appId}&auth=${authValue}&time=${timeValue}&appKey=${authOptions.appKey}"
+                if (SimApiUtil.md5(signStr) == signValue) {
+                    let login = SimApiUtil.base64DecodeTo<SimApiLoginItem>(authValue)
+                    context.items["LoginInfo"] = login
+                }
+            }
+        }
+        next(context)
+    }
+}