fix(billing): extend quantity validation and saturating conversions to remaining paths

Bound max-tokens fields across all relay format validators, saturate
tiered-expression rounding and audio/tool/task token conversions, and
route legacy remix ratios through the guarded setter.

relay/channel/task/kling/adaptor.go

@@ -358,7 +358,8 @@ func (a *TaskAdaptor) ParseTaskResult(respBody []byte) (*relaycommon.TaskInfo, e
 			taskInfo.Url = video.Url
 		}
 		if tokens, err := strconv.ParseFloat(resPayload.Data.FinalUnitDeduction, 64); err == nil {
-			rounded := int(math.Ceil(tokens))
+			// 上游返回的扣费数值，饱和转换防止超大数值回绕成负数
+			rounded := common.QuotaFromFloat(math.Ceil(tokens))
 			if rounded > 0 {
 				taskInfo.CompletionTokens = rounded
 				taskInfo.TotalTokens = rounded