datetime 2

DSH 插件：自然语言相对时间 → ISO 解析工具（when），零依赖。

Per-turn clock and idle-gap context for DeepSeek Harness: one-line timestamp reading (weekday, date, time, UTC offset, IANA timezone) and previous turn end time at every conversation turn start, without breaking UI turn branching. dsh-message-datetime：每轮对