Mainplane harness pointer.

GET /<key>        the record of the harness with that ed25519 public key: {"url", "seq", "sig"}
PUT /<key>        {"url", "seq", "sig"}: sig is ed25519 over "<key> <url> <seq>", seq is unix
                  milliseconds and must go up. The record expires 30 days after its last PUT.
GET /name/<name>  the key of the harness that holds the network name: {"key"}
PUT /name/<name>  {"key", "seq", "sig"}: sig over "name <name> <key> <seq>", seq as above. A
                  key holds one name: a new one frees the one before. A name another key holds
                  is refused. It expires 30 days after its last PUT.
Keys and signatures are base64url without padding. Check sig yourself; the URL is a hint.