Mentions of the bot are occasionally missed

[emilyhunt]

Sometimes, mentions to the bot are missed. This seems to be an issue with Bluesky's notification system occasionally dropping notifications. I had a snoop around the bot's code this week, and couldn't really find a convincing reason why notifications would be dropped by it.

This could be fixed in a similar way to how notifications/get_stale_commands works to detect updates to multi-step commands: once every e.g. 30 minutes, it could search the network for '@bot.astronomy.blue' and coerce any mentions it hasn't seen into a new command.

However, some care would have to be taken here. I don't think the database of botactions currently stores the URI and CID of the original post that a mention was from: meaning that any mentions of the bot that are a part of a thread do not have their URI stored. The solution to this would be to add new database columns for the original URI and CID of a command.