-- Run this once in phpMyAdmin (select the database, then SQL tab).
-- Companion to migration_09_screen_message.sql. The main (reply-keyboard)
-- menu message can never be tracked as the editable "screen" anchor — see
-- the comment above screen_menu() in includes/screen.php for why — so it
-- gets its own small anchor here, purely so the previous bottom-menu
-- bubble is cleaned up whenever a new one is sent.
ALTER TABLE users
    ADD COLUMN menu_message_id BIGINT NULL AFTER screen_message_id;