Launched MVP on the Slack App Directory

It's live on https://app.slack.com/apps/AT1NHTAAE-smithy

This was the first "proper" Slack app that we built, and in particular one that extended core Slack functionality in a mostly invisible fashion, so there was a lot to learn and a lot of trial and error.

Originally, the MVP was meant to be just creating Smithy threads as an authenticated users and automatic non-threaded message cleanup. We quickly realised that threads on their own were only half of the story and a way to mark threads as closed provided a significant amount of additional value to a channel's conversations. So that was the third MVP feature that we decided to launch with.