MRBS 1.12.2 等保2.0二级整改完整提交

包含：登录失败锁定、90天密码有效期、30分钟会话超时、
强制改密、登录审计日志、屏幕水印、企业背景图、
备案信息固定底部、favicon、JS空集合保护、
会话过期体验优化（403 JSON）、display_errors 关闭、
固定 key 根治 Integrity check failed 等全部改动

注意：config.inc.php/.htaccess/.user.ini 含敏感信息，
通过 .gitignore 排除，勿推送到公开仓库。

upgrade/26/mysql.sql

@@ -0,0 +1 @@
+# Nothing to do

upgrade/26/post.inc

@@ -0,0 +1,10 @@
+<?php
+namespace MRBS;
+
+?>
+
+<script>
+//<![CDATA[
+  alert('If you have just upgraded to MRBS 1.4.6 or later and had previously configured MRBS with $unicode_encoding = 0, you MUST read and follow the instructions in UPGRADE to convert your database to UTF-8');
+//]];
+</script>