Automatic backups

Nobody remembers to back up before a raid. With automatic backups, the bot does it every day on its own.

• On by default: every server has them from the start - the first one follows within a few minutes of adding the bot. Servers that added it before automatic backups existed have them on too, unless their owner switched them off.
• /backup auto shows whether they're on, when the next one runs, the newest automatic backup and how many are kept. Only the server owner gets the Turn off / Turn on buttons; admins see the state. Switched back on, the next one follows within a few minutes.
• When: once a day, at a fixed time per server (shown in your local time) - spread over the day, so not all servers are backed up at once. If the bot was offline at that time, it catches up once it's back.
• Only when something changed: if the server looks exactly like at the last automatic backup, none is created.
• Contents: everything /backup create backs up, except files attached to messages - those would take up far too much space every day. The messages themselves are backed up; when loaded, they name their files as "not backed up". Emojis, stickers and sounds are included. For a backup with attachments, use /backup create.
• What's kept - 11 slots of their own, apart from the 5 manual ones:

  Slots	What	Reaches back
  7	The newest backup of each of the last 7 days that had one	1 week
  4	Before those: the newest backup of each of 4 weeks (ISO weeks, UTC)	1 more month

  Days without changes don't use up a slot, so on a quiet server the backups reach further back. Older automatic backups are deleted as new ones come in.

• Automatic backups show up in /backup list (marked 🕒), can be inspected, compared, loaded and - by the owner - deleted like manual ones. Admins can't push them out by creating manual backups.
• Switched off, no new ones are created; the existing ones are kept. /backup check and /backup list point it out while they're off.