feat(federation): enrich RemoteActor with bio, banner, followers/following URLs

Bumps k-ap to 0.3.1 which adds bio, banner_url, followers_url,
following_url, and also_known_as to RemoteActor. These are populated
from fetched actor JSON at follow/ingest time so followers and following
listings no longer return null profile fields.

Adds migration 015 for the new remote_actors columns, updates all JOIN
queries in postgres-federation to select and return the new fields, and
maps them through k_ap_actor_to_domain.

Also fixes clippy: remove empty line after doc comment in port.rs.

crates/bootstrap/Cargo.toml

@@ -14,7 +14,7 @@ postgres = { workspace = true }
 postgres-search = { workspace = true }
 postgres-federation = { workspace = true }
 activitypub = { workspace = true }
-k-ap = { version = "0.3.0", registry = "gitea" }
+k-ap = { version = "0.3.1", registry = "gitea" }
 serde_json = { workspace = true }
 anyhow = { workspace = true }
 nats = { workspace = true }