fix: 缩放 ThorChatCompletionsResponse.Usage.TotalTokens 按 multiplier

当 Usage.TotalTokens 不为 null 时，按 multiplier 进行四舍五入缩放；与 PromptTokens/CompletionTokens 的缩放逻辑保持一致，修复 TotalTokens 未被缩放的问题。

Yi.Abp.Net8/module/ai-hub/Yi.Framework.AiHub.Domain.Shared/Dtos/OpenAi/ThorChatCompletionsResponse.cs

@@ -73,6 +73,12 @@ public record ThorChatCompletionsResponse
                 (int)Math.Round((this.Usage.CompletionTokens ?? 0) * multiplier);
             this.Usage.PromptTokens =
                 (int)Math.Round((this.Usage.PromptTokens ?? 0) * multiplier);
+
+            if (this.Usage.TotalTokens is not null)
+            {
+                this.Usage.TotalTokens =
+                    (int)Math.Round((this.Usage.TotalTokens ?? 0) * multiplier);
+            }
         }
     }
 }