Bluesky/atproto support

[legowerewolf]

Is Bluesky support in the cards? I understand that Bluesky doesn't use the <link rel="me" /> thing - they prefer domain verification via DNS record or .well-known URI - but how hard would it be to add support for at least Bluesky <link> tags, if not domain verification in full?

[camdecoster]

It's not possible right now with the current implementation of Streetpass for two reasons:

1. Streetpass attempts to fetch the profile URL for rel=me links (probably to verify that they're valid). Presently, Bluesky doesn't include the 'Access-Control-Allow-Origin' header in the response to a CORS request generated by Streetpass. As such, the request fails and the link is ignored.
2. Streetpass attempts to get profile information by querying the server for WebFinger information. Bluesky doesn't support WebFinger right now.

It would be possible to refactor Streetpass to work around these issues, but that might be a big lift.

[camdecoster]

Alright, I put together a draft PR to add Bluesky support in #77. Bluesky has a public API endpoint to get profile information for users, so I just used that instead of WebFinger.