refactor: BaseModel 主键列名统一 uid→id

- BaseModel 移除 gorm column:uid 和 json:uid 标签，统一为 id
- 更新 8 个 repository 文件中 28 处 raw SQL 列引用 (uid→id)
- 更新 3 个前端 JS 文件中 14 处 API 响应字段引用 (uid→id)
- 添加数据库迁移 SQL 脚本 (docs/migrations/001_uid_to_id.sql)

internal/repository/user_repo.go

@@ -69,7 +69,7 @@ func (r *UserRepo) ExistsByUsername(username string) (bool, error) {
 func (r *UserRepo) ExistsByEmailExclude(email string, excludeUID uint) (bool, error) {
 	var count int64
 	err := r.db.Model(&model.User{}).
-		Where("email = ? AND uid != ?", email, excludeUID).
+		Where("email = ? AND id != ?", email, excludeUID).
 		Count(&count).Error
 	return count > 0, err
 }
@@ -77,7 +77,7 @@ func (r *UserRepo) ExistsByEmailExclude(email string, excludeUID uint) (bool, er
 // FindByIDForAuth 认证专用查询：返回 uid/email/username/avatar/role/status
 func (r *UserRepo) FindByIDForAuth(userID uint) (*model.User, error) {
 	var user model.User
-	err := r.db.Select("uid", "email", "username", "avatar", "role", "status", "exp").
+	err := r.db.Select("id", "email", "username", "avatar", "role", "status", "exp").
 		First(&user, userID).Error
 	if err != nil {
 		return nil, err
@@ -88,7 +88,7 @@ func (r *UserRepo) FindByIDForAuth(userID uint) (*model.User, error) {
 // FindByIDUnscoped 管理后台专用：含软删除用户，用于解锁/封禁等操作
 func (r *UserRepo) FindByIDUnscoped(userID uint) (*model.User, error) {
 	var user model.User
-	err := r.db.Unscoped().Select("uid", "email", "username", "role", "status", "deleted_at").
+	err := r.db.Unscoped().Select("id", "email", "username", "role", "status", "deleted_at").
 		First(&user, userID).Error
 	if err != nil {
 		return nil, err
@@ -98,12 +98,12 @@ func (r *UserRepo) FindByIDUnscoped(userID uint) (*model.User, error) {
 
 // UpdateStatus 更新用户状态（含软删除用户，locked 状态变更需要）
 func (r *UserRepo) UpdateStatus(uid uint, status string) error {
-	return r.db.Unscoped().Model(&model.User{}).Where("uid = ?", uid).Update("status", status).Error
+	return r.db.Unscoped().Model(&model.User{}).Where("id = ?", uid).Update("status", status).Error
 }
 
 // UpdateRole 更新用户角色（仅 owner 调用）
 func (r *UserRepo) UpdateRole(uid uint, role string) error {
-	return r.db.Model(&model.User{}).Where("uid = ?", uid).Update("role", role).Error
+	return r.db.Model(&model.User{}).Where("id = ?", uid).Update("role", role).Error
 }
 
 // Update 全量更新用户信息
@@ -113,12 +113,12 @@ func (r *UserRepo) Update(user *model.User) error {
 
 // SoftDelete GORM 软删除（设 DeletedAt），用于 locked 状态释放邮箱
 func (r *UserRepo) SoftDelete(uid uint) error {
-	return r.db.Where("uid = ?", uid).Delete(&model.User{}).Error
+	return r.db.Where("id = ?", uid).Delete(&model.User{}).Error
 }
 
 // Restore 恢复软删除（清 DeletedAt）
 func (r *UserRepo) Restore(uid uint) error {
-	return r.db.Unscoped().Model(&model.User{}).Where("uid = ?", uid).Update("deleted_at", nil).Error
+	return r.db.Unscoped().Model(&model.User{}).Where("id = ?", uid).Update("deleted_at", nil).Error
 }
 
 // buildSearchQuery 构建搜索/筛选的公共查询条件
@@ -141,7 +141,7 @@ func (r *UserRepo) buildSearchQuery(keyword, role, status string) *gorm.DB {
 func (r *UserRepo) SearchUsers(keyword, role, status string, offset, limit int) ([]model.User, error) {
 	var users []model.User
 	err := r.buildSearchQuery(keyword, role, status).
-		Order("uid ASC").Offset(offset).Limit(limit).Find(&users).Error
+		Order("id ASC").Offset(offset).Limit(limit).Find(&users).Error
 	return users, err
 }