Link Discourse ID with member ID #7
Description
As a follow-on task from #3 we should link the member's discourse ID with the membership database ID. This could be done either by polling for new members, or through a webhook from Discourse. If we can use the discourse invite itself to link the records then that would be ideal, otherwise we can just use the email address.
We will also have to associate all our existing members. We can make a first pass by matching known emails from both systems. Any missing or duplicate entries from either side can then be fixed manually.