fix: 修复Anthropic接口TokenUsage序列化及HttpClient创建方式问题

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

@@ -546,7 +546,11 @@ public class AiGateWayManager : DomainService
         {
             await foreach (var responseResult in completeChatResponse)
             {
-                tokenUsage = responseResult.Item2?.TokenUsage;
+                //message_start是为了保底机制
+                if (responseResult.Item1.Contains("message_delta")||responseResult.Item1.Contains("message_start"))
+                {
+                    tokenUsage = responseResult.Item2?.TokenUsage;
+                }
                 backupSystemContent.Append(responseResult.Item2?.Delta?.Text);
                 await WriteAsEventStreamDataAsync(httpContext, responseResult.Item1, responseResult.Item2,
                     cancellationToken);