feat(dcauth): 移除机器码，改用纯设备码认证

- DCAuth 协议升级到 v2，签名原文只含设备码；客户端 2.0.0，旧版本返回 426
- 删除客户端机器码采集、后端 machine_code_* 字段与日志、后台机器码展示
- 102 迁移在生产执行前直接改为无机器码结构；SQL 守卫仅放行该文件
- Mock 短信不启用每日限额；修复慢电脑首次启动的协议转发竞态
- 新增 macOS DCAuth.app 打包脚本，注册 dcauth:// 协议，浏览器可直接唤起

apps/backend/src/db/migrations/102_admin_phone_device_auth.sql

@@ -52,8 +52,6 @@ CREATE TABLE IF NOT EXISTS admin_user_devices (
   user_id BIGINT NOT NULL REFERENCES admin_users(id) ON DELETE CASCADE,
   device_id TEXT NOT NULL,
   public_key TEXT NOT NULL,
-  machine_code_hash TEXT NOT NULL,
-  machine_code_mask TEXT NOT NULL DEFAULT '',
   client_version TEXT NOT NULL DEFAULT '',
   status TEXT NOT NULL DEFAULT 'active',
   bound_at TIMESTAMPTZ NOT NULL,
@@ -81,8 +79,6 @@ CREATE TABLE IF NOT EXISTS admin_device_challenges (
   user_id BIGINT REFERENCES admin_users(id) ON DELETE SET NULL,
   device_id TEXT NOT NULL DEFAULT '',
   public_key TEXT NOT NULL DEFAULT '',
-  machine_code_hash TEXT NOT NULL DEFAULT '',
-  machine_code_mask TEXT NOT NULL DEFAULT '',
   client_version TEXT NOT NULL DEFAULT '',
   device_ticket_hash TEXT NOT NULL DEFAULT '',
   expires_at TIMESTAMPTZ NOT NULL,
@@ -100,8 +96,6 @@ CREATE INDEX IF NOT EXISTS idx_admin_device_challenges_user
 
 ALTER TABLE admin_login_logs
   ADD COLUMN IF NOT EXISTS login_method TEXT NOT NULL DEFAULT 'password';
-ALTER TABLE admin_login_logs
-  ADD COLUMN IF NOT EXISTS machine_code_mask TEXT NOT NULL DEFAULT '';
 
 ALTER TABLE admin_sessions
   ADD COLUMN IF NOT EXISTS device_id TEXT NOT NULL DEFAULT '';
@@ -109,8 +103,7 @@ ALTER TABLE admin_sessions
 COMMENT ON COLUMN admin_users.phone IS '后台账号绑定手机号，用于登录短信验证码';
 COMMENT ON COLUMN admin_users.test_account IS '技术测试账号：允许仅账号密码登录，跳过短信和 DCAuth 设备验证';
 COMMENT ON TABLE admin_sms_codes IS '后台登录短信验证码（哈希存储、一次性消费）';
-COMMENT ON TABLE admin_user_devices IS '后台账号绑定的 DCAuth 设备（公钥 + 机器码哈希）';
+COMMENT ON TABLE admin_user_devices IS '后台账号绑定的 DCAuth 设备（公钥指纹）';
 COMMENT ON TABLE admin_device_challenges IS 'DCAuth 设备认证 challenge 与一次性 ticket';
 COMMENT ON COLUMN admin_login_logs.login_method IS 'password / sms_device';
-COMMENT ON COLUMN admin_login_logs.machine_code_mask IS '登录设备机器码脱敏值';
 COMMENT ON COLUMN admin_sessions.device_id IS '登录会话绑定的设备 ID';