feat(billing): 火山方舟视频计费 - 支持真实 Token 预授权与结算

Refs #228

Co-authored-by: MasterChiefCN <49179444+MasterChiefCN@users.noreply.github.com>

backend/internal/repository/finance.go

@@ -387,7 +387,9 @@ func (r *Repository) BillingUsage(orderID string) (*BillingUsage, error) {
 
 func billingUsage(db *gorm.DB, orderID string) (*BillingUsage, error) {
 	var log model.ApiCallLog
-	err := db.Where("billing_order_id = ? AND billable = ? AND status = ? AND usage_available = ?", orderID, true, model.ApiCallStatusSucceeded, true).
+	// 异步视频的真实 usage 由非计费的轮询请求返回；订单本身已经限定了归属，
+	// 结算应读取同订单最新的成功 usage，而不是只看创建请求。
+	err := db.Where("billing_order_id = ? AND status = ? AND usage_available = ?", orderID, model.ApiCallStatusSucceeded, true).
 		Order("created_at desc").First(&log).Error
 	if errors.Is(err, gorm.ErrRecordNotFound) {
 		return nil, ErrBillingUsageUnavailable
@@ -615,6 +617,9 @@ func tokenUsageAmount(order model.BillingOrder, usage *BillingUsage) (int64, err
 	if usage == nil {
 		return 0, ErrBillingUsageUnavailable
 	}
+	if order.Capability == "video" && usage.OutputTokens <= 0 {
+		return 0, ErrBillingUsageUnavailable
+	}
 	input := usage.InputTokens - usage.CachedTokens
 	if input < 0 {
 		input = 0