fix: close platform admin final audit findings

backend/api/internal/models/fin_reconciliation.go

@@ -7,10 +7,10 @@ import (
 
 // FinReconciliation 对应 fin_reconciliation，保存渠道对账记录。
 type FinReconciliation struct {
-	Entity
-	Channel          string    `gorm:"column:channel;type:varchar(32);not null;index" json:"channel"`
-	BillDate         time.Time `gorm:"column:bill_date;type:date;not null" json:"bill_date"`
-	DifferenceAmount int64     `gorm:"column:difference_amount;not null;default:0" json:"difference_amount"`
+	Entity                     // 公共实体字段
+	Channel          string    `gorm:"column:channel;type:varchar(32);not null;index" json:"channel"`        // channel 业务字段
+	BillDate         time.Time `gorm:"column:bill_date;type:date;not null" json:"bill_date"`                 // bill_date 业务字段
+	DifferenceAmount int64     `gorm:"column:difference_amount;not null;default:0" json:"difference_amount"` // difference_amount 业务字段
 }
 
 func init()                                        { database.AppendMigrate(&FinReconciliation{}) }