【中文说明】用于解释、验证或编写cron定时表达式，列出后续运行时间，并检查日期规则、时区、夏令时及任务重叠风险。粘贴表达式或调度配置，同时说明运行平台、时区和任务耗时，避免不同系统的语法差异造成误判。 Explains any cron expression in plain English, lists the next run times, and flags pitfalls such as the day-of-month OR day-of-week rule, dates that never occur, DST gaps, UTC versus local time, and overlapping jobs. Includes a tested stdlib Python checker for crontab files.
