login: block concurrent login, single-factor auth for staff/viewer

setup.php

@@ -103,6 +103,8 @@ CREATE TABLE IF NOT EXISTS `user` (
   `verify_expires_at` datetime    DEFAULT NULL,
   `login_attempts`   int(11)      NOT NULL DEFAULT 0,
   `locked_until`     datetime     DEFAULT NULL,
+  `session_token`    varchar(64)  DEFAULT NULL,
+  `session_token_at` datetime     DEFAULT NULL,
   PRIMARY KEY (`user_id`),
   UNIQUE KEY `username` (`username`),
   UNIQUE KEY `email` (`email`),
@@ -522,9 +524,11 @@ CREATE TABLE IF NOT EXISTS `td_stock` (
   `description`   text         NOT NULL DEFAULT '',
   `status`        int(3)       NOT NULL DEFAULT 0,
   `log`           mediumtext   NOT NULL DEFAULT '{}',
+  `updated_at`    datetime     DEFAULT NULL,
   PRIMARY KEY (`id`),
   KEY `company_id` (`company_id`),
-  KEY `product_id` (`product_sku`)
+  KEY `product_id` (`product_sku`),
+  KEY `updated_at` (`updated_at`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb3;
 ", 'td_stock (base template)');