feat: reminders

[Vuks69]

Relevant module

Community

Flow

• User can set a reminder for relative time, or a specific date/time, with a comment
  • /remindme when:in 2 hours what:cookies are done
  • /remindme when:1d5m what:it is a new day
  • /remindme when:Tuesday 9:00 GMT what:It is Tuesday my dudes
  • /remindme when:04.05.2027 what:May the Fourth be with you
• When reminder is due, bot sends a DM with the comment
  • Maybe also channel link to where the bot was invoked?
• User can see list of pending and past (within last week?) reminders

Concerns

None that I can see - the feature is entirely 1:1 between bot and user.