feat: 完成agent接口

Yi.Abp.Net8/module/ai-hub/Yi.Framework.AiHub.Domain/Managers/AiGateWayManager.cs

@@ -234,7 +234,7 @@ public class AiGateWayManager : DomainService
                     tokenUsage = data.Usage;
                 }
 
-                var message = System.Text.Json.JsonSerializer.Serialize(data, ThorJsonSerializer.DefaultOptions);
+                var message = JsonSerializer.Serialize(data, ThorJsonSerializer.DefaultOptions);
                 backupSystemContent.Append(data.Choices.FirstOrDefault()?.Delta.Content);
                 // 将消息加入队列而不是直接写入
                 messageQueue.Enqueue($"data: {message}\n\n");