Introduced a new batch process to handle users lacking an `account_status` meta efficiently. Refactored legacy methods, added async scheduling, and created helper functions to manage and track progress. These changes improve performance and reliability for large user bases.
* updated filters by status, avoid slow queries for getting users count;
* updated bulk-actions for changing statuses (moved to WP native dropdown)
* separate handlers for changing user statuses on wp-admin and frontend (partially implemented);
* created class UM()->common()->users() to handle user statuses in more clear format;
* deprecated old hooks and old functions