Star a project

[cloudhead]

It would be nice to have a way of bookmarking / signaling interest in a project, like on github.

To avoid the spam issue, we could hide stars from users who don't have a radicle.eth name. Only they would see their own stars, but they wouldn't be visible publicly.

To avoid the tx fee issue we would use a signed message stored off-chain instead of a transaction. The question is where? Cermaic? IPFS? Sia?