fix: 修复域能相关数据表缺失及首次查询报错

- AutoMigrate 添加 EnergyLog、PostEnergizeLog、DailyExpSummary 三张表
- GetDailyEnergizeExp 无记录时返回 nil, nil 而非 gorm.ErrRecordNotFound
- 调用方增加 summary nil 检查，防止空指针

internal/service/energy_service.go

@@ -160,7 +160,7 @@ func (s *EnergyService) Energize(energizerID uint, postID uint, amount int) (int
 
 		summary, err := txRepo.GetDailyEnergizeExp(energizerID, today)
 		currentDaily := 0
-		if err == nil {
+		if err == nil && summary != nil {
 			currentDaily = summary.ExpEarned
 		}
 
@@ -305,7 +305,7 @@ func (s *EnergyService) GetEnergyInfo(userID uint) (*EnergyInfo, error) {
 
 	dailyExp := 0
 	summary, err := s.repo.GetDailyEnergizeExp(userID, today)
-	if err == nil {
+	if err == nil && summary != nil {
 		dailyExp = summary.ExpEarned
 	}