scale to allow any number of instances

At the moment, only one of these can run at a time for a combination of telegram bot and xmpp client.

These two responsibilities could be split out:
- one process to receive telegram follow/unfollow messages and create subscriptions
- another process to receive new post notifications and write to telegram

Ideally we could replace telegram polling could be replaced by web hooks fairly easily. The XMPP subscriptions might be harder to scale

Start by tracing how the Telegram bot and XMPP client currently receive messages and notifications, including the Telegram polling and subscription paths. Compare the proposed split between subscription creation and post delivery with the webhook and XMPP scaling concerns. Done means multiple instances can run without conflicting responsibilities or duplicate handling.

Written by the indexing model from the issue text.