Gossip (unstable, not yet master) now does basic blossom.

It only uploads to 1 server and doesn't create any fallback mirrors.
It doesn't sync your blossom server config.
It doesn't utilize imeta->fallback fields from other people's notes.

But it does let you specify a blossom server (Settings > Posting > Blossom servers), lets you pick a file from your filesystem, uploads it and reports the error (click it away after you read it) or inserts the link into your edit area.

And chorus handles the other end as I finished its blossom support yesterday.

Tested against:
- chorus.mikedilger.com:444 (works for me as I'm configured, but it won't work for you).
- blossom.primal.net
- blossom.nostr.hu
- cdn.hzrd149.com
- cdn.satellite earth (402 Payment Required)
- nostrmedia.com (500 Internal Server Error)