fix: 删稿扣域能增加一致性保障（事务包裹 + 有限重试）

- DeductOnDeletePost 使用 DB 事务包裹 AddEnergy + CreateEnergyLog，确保扣域能写流水原子性
- Controller 层增加 3 次指数退避重试（100ms/200ms/400ms），全部失败后 log.Printf 记录
- 保持原行为：扣减无视负数，失败不阻塞删稿主流程

internal/service/energy_service.go

@@ -254,20 +254,25 @@ func (s *EnergyService) RefundOnRenameReject(userID uint) error {
 }
 
 // DeductOnDeletePost 删稿扣域能（扣文章作者的域能，无视负数）
+// 事务包裹：确保扣域能 + 写流水原子性
 func (s *EnergyService) DeductOnDeletePost(authorUserID uint, postID uint) error {
-	if err := s.repo.AddEnergy(authorUserID, EnergyDeletePost); err != nil {
-		return fmt.Errorf("扣减删稿域能失败: %w", err)
-	}
+	return s.db.Transaction(func(tx *gorm.DB) error {
+		txRepo := s.repo.WithTx(tx)
 
-	log := &model.EnergyLog{
-		UserID:      authorUserID,
-		Amount:      EnergyDeletePost,
-		Type:        model.EnergyTypeDeletePost,
-		RelatedType: "post",
-		RelatedID:   postID,
-		Description: "删除文章消耗 2.0 域能",
-	}
-	return s.repo.CreateEnergyLog(log)
+		if err := txRepo.AddEnergy(authorUserID, EnergyDeletePost); err != nil {
+			return fmt.Errorf("扣减删稿域能失败: %w", err)
+		}
+
+		log := &model.EnergyLog{
+			UserID:      authorUserID,
+			Amount:      EnergyDeletePost,
+			Type:        model.EnergyTypeDeletePost,
+			RelatedType: "post",
+			RelatedID:   postID,
+			Description: "删除文章消耗 2.0 域能",
+		}
+		return txRepo.CreateEnergyLog(log)
+	})
 }
 
 // AdminAdjust 后台调整用户域能