Cacher bot

[haadcode]

We should deploy cacher bot(s) to the orbit network to make sure the messages are always reachable and persisted in the network.

The bot should run on a public IP (ie. not behind a firewall or NAT) so that it's reachable by everyone.

The user should be able to summon (invite) the bot to a channel to make sure it's persisted.

Long-term solution should include "load balancing" so that there are multiple bots handling this responsibility. Ideally, anyone can add a cacher bot to the network.