CREATE TABLE login_captcha_policy (
  singleton boolean PRIMARY KEY DEFAULT true CHECK (singleton),
  saas_mode text NOT NULL DEFAULT 'image' CHECK (saas_mode IN ('image','tencent')),
  mini_mode text NOT NULL DEFAULT 'image' CHECK (mini_mode IN ('image','tencent')),
  version bigint NOT NULL DEFAULT 1 CHECK (version > 0),
  updated_at timestamptz NOT NULL DEFAULT now()
);
INSERT INTO login_captcha_policy(singleton) VALUES(true);