fix anwser token and database issus

internal/db/questions.go

@@ -92,7 +92,7 @@ func (db *questions) Create(ctx context.Context, opts CreateQuestionOptions) (*Q
 	question := Question{
 		FromIP:            opts.FromIP,
 		UserID:            opts.UserID,
-		Token:             randstr.String(6),
+		Token:             randstr.String(12),
 		Content:           opts.Content,
 		ReceiveReplyEmail: opts.ReceiveReplyEmail,
 		AskerUserID:       opts.AskerUserID,
@@ -401,17 +401,19 @@ func (db *questions) DeleteByID(ctx context.Context, id uint) error {
 	}
 
 	// 级联清理子表：追问与上传图片，避免删除提问后残留孤儿记录。
-	if err := FollowUps.DeleteByQuestionID(ctx, id); err != nil {
+	// 直接用本 store 的 *gorm.DB 构造子 store，避免依赖包级全局单例
+	// （全局单例仅在 db.Init 装配，测试/部分初始化场景下为 nil 会 panic）。
+	if err := NewFollowUpsStore(db.DB).DeleteByQuestionID(ctx, id); err != nil {
 		logrus.WithContext(ctx).WithError(err).Errorf("Failed to cascade delete follow ups for question %d", id)
 	}
-	if err := UploadImages.DeleteByQuestionID(ctx, id); err != nil {
+	if err := NewUploadImagesStore(db.DB).DeleteByQuestionID(ctx, id); err != nil {
 		logrus.WithContext(ctx).WithError(err).Errorf("Failed to cascade delete upload images for question %d", id)
 	}
 
 	// 回退定量收集计数：删除提问等价于少一条已收集内容，
 	// 否则达上限后即便删掉旧提问，功能仍会显示 quota_reached 关闭，须手动重置计数。
 	if question.UserID != 0 {
-		if err := FeatureControls.IncrementQuota(ctx, question.UserID, FeatureQuestion, -1); err != nil {
+		if err := NewFeatureControlsStore(db.DB).IncrementQuota(ctx, question.UserID, FeatureQuestion, -1); err != nil {
 			logrus.WithContext(ctx).WithError(err).Errorf("Failed to decrement question quota for user %d", question.UserID)
 		}
 	}