feat(matrix/fediverse): allow users to favorite, reblog, and redact Fediverse posts from Matrix, using m.reaction on our new meta field.
feat(fediverse): add suggestions for follow/unfollow commands.
refactor(matrix/fediverse): add meta field for commands by reaction, and commands by reply.
refactor(fediverse): relax polling on timeline/notifs thru new handling.
