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/adapters/activitypub/src/service.rs

@@ -114,11 +114,11 @@ fn k_ap_actor_to_domain(a: k_ap::RemoteActor) -> DomainRemoteActor {
         avatar_url: a.avatar_url,
         outbox_url: a.outbox_url,
         last_fetched_at: chrono::Utc::now(),
-        bio: None,
-        banner_url: None,
-        also_known_as: None,
-        followers_url: None,
-        following_url: None,
+        bio: a.bio,
+        banner_url: a.banner_url,
+        also_known_as: a.also_known_as.into_iter().next(),
+        followers_url: a.followers_url,
+        following_url: a.following_url,
         attachment: vec![],
     }
 }