fix(task): attribute async task usage log to the initiating node (#5684)

Async task usage logs (LogQuotaData node dimension) were recorded
under whichever node happened to poll the task to completion, not the
node that submitted it. For token/adaptor-billed video tasks the
pre-deduction is often 0, so the entire quota landed on the last
polling node.

Snapshot common.NodeName into TaskPrivateData at submit time and use
it when writing the settlement consume log; fall back to the current
node when empty so existing tasks stay compatible.

controller/relay.go

@@ -583,6 +583,7 @@ func RelayTask(c *gin.Context) {
 		task.PrivateData.BillingSource = relayInfo.BillingSource
 		task.PrivateData.SubscriptionId = relayInfo.SubscriptionId
 		task.PrivateData.TokenId = relayInfo.TokenId
+		task.PrivateData.NodeName = common.NodeName
 		task.PrivateData.BillingContext = &model.TaskBillingContext{
 			ModelPrice:      relayInfo.PriceData.ModelPrice,
 			GroupRatio:      relayInfo.PriceData.GroupRatioInfo.GroupRatio,