908d92a7e8
safeKey kept ASCII only, so "Встреча с Аней" and "Обед с мамой" both reduced to "--" and shared one key on one day. The second event of the day overwrote the first, silently, and his calendar is Russian. Letters and digits in any script now pass. Migration #18 deletes the rows written under the old rule instead of rewriting them: a calendar fact is derived, the next poll writes the day again, and a stale row reads as an extra meeting.