fix: record zero OpenAI usage logs

backend/internal/service/openai_gateway_service.go

@@ -5041,13 +5041,6 @@ func (s *OpenAIGatewayService) RecordUsage(ctx context.Context, input *OpenAIRec
 		s.rateLimitService.ResetOpenAI403Counter(ctx, input.Account.ID)
 	}
 
-	// 跳过所有 token 均为零的用量记录——上游未返回 usage 时不应写入数据库
-	if result.Usage.InputTokens == 0 && result.Usage.OutputTokens == 0 &&
-		result.Usage.CacheCreationInputTokens == 0 && result.Usage.CacheReadInputTokens == 0 &&
-		result.Usage.ImageOutputTokens == 0 && result.ImageCount == 0 {
-		return nil
-	}
-
 	apiKey := input.APIKey
 	user := input.User
 	account := input.Account