Removed `bluesky` field from `actor.profile`. We can allow users to put link to their bluesky profile with their platform of choice instead. `publicKey` is splitted by key types. We usually want to fetch keys by their types rather than usage. Also usage can be differ by key type. string now uses a blob. The string record is largely enum type so we can easily extend it later without breaking changes. Signed-off-by: Seongmin Lee <git@boltless.me>