feat: migrate k-ap 0.1.10→0.3.1, fix AP gaps

- split FederationRepository into FollowRepository, ActorRepository, BlocklistRepository, ActivityRepository
- RemoteActor: 5 new fields (bio, banner_url, followers_url, following_url, also_known_as)
- ApObjectHandler split: get_local_objects_page/count_local_posts → ApContentReader trait
- builder API: positional args → named setters
- broadcast_create_note/update_note: add ApVisibility + mentioned_inboxes params
- backfill_outbox → import_remote_outbox
- ApUser: also_known_as Option<String> → Vec<String>, new fields

AP gaps fixed:
- add GET /users/{id}/followers + /following with content negotiation
- wire EventPublisher into builder via FederationEventBridge adapter
- add display_name field full stack (domain→DB→API→AP)
- DB-side outbox pagination (get_local_reviews_page)
- set featured_url on ApUser

crates/domain/src/ports.rs

@@ -185,6 +185,7 @@ pub trait UserRepository: Send + Sync {
     async fn update_profile(
         &self,
         user_id: &UserId,
+        display_name: Option<String>,
         bio: Option<String>,
         avatar_path: Option<String>,
         banner_path: Option<String>,
@@ -398,4 +399,11 @@ pub trait LocalApContentQuery: Send + Sync {
     async fn get_movie_by_id(&self, movie_id: &MovieId) -> Result<Option<Movie>, DomainError>;
 
     async fn count_local_posts(&self) -> Result<u64, DomainError>;
+
+    async fn get_local_reviews_page(
+        &self,
+        user_id: &UserId,
+        before: Option<chrono::NaiveDateTime>,
+        limit: usize,
+    ) -> Result<Vec<DiaryEntry>, DomainError>;
 }