Add ActivityPub support to Known [3000 USD]

Known should support inbound and outbound ActivityPub, in order to achieve full compatibility with fediverse tools like Mastodon.

This includes:

Posting
Likes, reposts, etc
A feed of followed accounts

This also includes a default feed of accounts, so that a Known site doesn't feel empty when a site owner logs into it for the first time.

toot: toot

blog: blog

apply: Gitcoin