feat: add email_send_log table to track email sends and registration status

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/storage/dao/email_send_log.go

@@ -0,0 +1,50 @@
+package dao
+
+import (
+	"gorm.io/gorm"
+)
+
+type EmailSendStatus int8
+
+const (
+	EmailSendStatusSent       EmailSendStatus = 0 // 已发送，用户未注册
+	EmailSendStatusRegistered EmailSendStatus = 1 // 用户已完成注册
+)
+
+type EmailSendLog struct {
+	BaseModel
+	Email  string          `gorm:"column:email;type:varchar(255);not null;comment:邮箱地址" json:"email"`
+	Status EmailSendStatus `gorm:"column:status;type:tinyint;not null;default:0;comment:状态: 0=已发送未注册 1=已注册" json:"status"`
+}
+
+func (e *EmailSendLog) TableName() string {
+	return "email_send_log"
+}
+
+type EmailSendLogDao struct{}
+
+func NewEmailSendLogDao() *EmailSendLogDao {
+	return &EmailSendLogDao{}
+}
+
+func (d *EmailSendLogDao) Create(tx *gorm.DB, log *EmailSendLog) error {
+	return tx.Create(log).Error
+}
+
+func (d *EmailSendLogDao) GetLatestByEmail(tx *gorm.DB, email string) (*EmailSendLog, error) {
+	var record EmailSendLog
+	err := tx.Where("email = ?", email).Order("id DESC").First(&record).Error
+	if err != nil {
+		if err == gorm.ErrRecordNotFound {
+			return nil, nil
+		}
+		return nil, err
+	}
+	return &record, nil
+}
+
+func (d *EmailSendLogDao) MarkRegistered(tx *gorm.DB, email string) error {
+	return tx.Model(&EmailSendLog{}).
+		Where("email = ? AND status = ?", email, EmailSendStatusSent).
+		Update("status", EmailSendStatusRegistered).Error
+}