Add DB Restore to Maintenance

The function to restore a backup has been added. The "pending" backups are now deleted after the restore.
A backup is also created before a restore, but it is also deleted after the restore. When restoring, the existing database is overwritten by the backup.

CSS adjustments were made to eliminate errors in darkmode and lightmode.

front/css/dark-patch.css

@@ -662,3 +662,5 @@ input[type="password"]::-webkit-caps-lock-indicator {
   color: #444;
 }
 
+.db_info_table_cell:nth-child(1) {background: #272c30}
+.db_info_table_cell:nth-child(2) {background: #272c30}