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/34/mysql.sql

@@ -0,0 +1,13 @@
+# Add a month_relative column so that monthly sameday repeats can be converted to the
+# new format.   The conversion itself is done in post.inc
+
+# We save the current value of the timestamp before updating and restore it 
+# afterwards because we do not want the timestamp to be changed by this operation.
+# The restoration is done in the next upgrade because we need to operate on the table
+# first using post.inc
+ALTER TABLE %DB_TBL_PREFIX%repeat
+ADD COLUMN saved_ts DATETIME;
+UPDATE %DB_TBL_PREFIX%repeat SET saved_ts=timestamp;
+
+ALTER TABLE %DB_TBL_PREFIX%repeat
+ADD COLUMN month_relative varchar(4) DEFAULT NULL;