-- 独立管理员账号表（与 App 用户 users 表完全分离）
CREATE TABLE IF NOT EXISTS admin_users (
    id             INT AUTO_INCREMENT PRIMARY KEY,
    username       VARCHAR(50)  NOT NULL UNIQUE,
    password_hash  VARCHAR(255) NOT NULL,
    name           VARCHAR(50)  NOT NULL DEFAULT '',
    status         VARCHAR(20)  NOT NULL DEFAULT 'active',  -- active / disabled
    created_at     TIMESTAMP    NOT NULL DEFAULT CURRENT_TIMESTAMP,
    last_login_at  DATETIME     NULL,
    KEY idx_status (status)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

-- 操作日志增加操作者字段
ALTER TABLE admin_logs ADD COLUMN admin_user_id INT NULL AFTER id;
ALTER TABLE admin_logs ADD INDEX idx_admin_user (admin_user_id);