feat: add short IM user numbers

docs/admin-adfahi-research/sql/IM-Server改造.sql

@@ -8,6 +8,53 @@
 SET NAMES utf8mb4;
 USE `tinode`;
 
+-- ============================================================
+-- 0. User account number.
+-- account_no is the short user number shown in Admin. The real primary key
+-- im_users.id remains the internal Tinode/Snowflake user ID.
+-- Existing users are backfilled from 1000 by created time; new users are
+-- assigned by IM Server in the user creation transaction.
+-- ============================================================
+
+SET @sql := IF(
+  (SELECT COUNT(*) FROM information_schema.COLUMNS
+   WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'im_users' AND COLUMN_NAME = 'account_no') = 0,
+  'ALTER TABLE `im_users` ADD COLUMN `account_no` int unsigned NOT NULL DEFAULT 0 COMMENT ''用户编号'' AFTER `id`',
+  'SELECT 1'
+);
+PREPARE stmt FROM @sql;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;
+
+SET @im_user_account_no := (
+  SELECT GREATEST(COALESCE(MAX(`account_no`), 999), 999)
+  FROM `im_users`
+  WHERE `account_no` > 0
+);
+
+UPDATE `im_users` AS u
+JOIN (
+  SELECT ordered.`id`, (@im_user_account_no := @im_user_account_no + 1) AS next_no
+  FROM (
+    SELECT `id`
+    FROM `im_users`
+    WHERE `account_no` = 0
+    ORDER BY `createdat`, `id`
+  ) AS ordered
+) AS seq ON seq.`id` = u.`id`
+SET u.`account_no` = seq.next_no
+WHERE u.`account_no` = 0;
+
+SET @sql := IF(
+  (SELECT COUNT(*) FROM information_schema.STATISTICS
+   WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'im_users' AND INDEX_NAME = 'uk_im_users_account_no') = 0,
+  'CREATE UNIQUE INDEX `uk_im_users_account_no` ON `im_users` (`account_no`)',
+  'SELECT 1'
+);
+PREPARE stmt FROM @sql;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;
+
 -- ============================================================
 -- 1. Applied runtime policy snapshots.
 -- policy_type: security, user_policy_groups, sensitive_words.