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/adapters/activitypub/src/event_handler.rs

@@ -8,7 +8,7 @@ use domain::{
 };
 use std::sync::Arc;
 
-use k_ap::ActivityPubService;
+use k_ap::{ActivityPubService, ApVisibility};
 
 use crate::objects::review_to_ap_object;
 use crate::urls::{actor_url, review_url};
@@ -170,7 +170,7 @@ impl ActivityPubEventHandler {
         let json = serde_json::to_value(obj)?;
 
         self.ap_service
-            .broadcast_update_note(user_id.value(), json)
+            .broadcast_update_note(user_id.value(), json, ApVisibility::Public, vec![])
             .await?;
 
         Ok(())
@@ -227,7 +227,7 @@ impl ActivityPubEventHandler {
         let json = serde_json::to_value(obj)?;
 
         self.ap_service
-            .broadcast_create_note(user_id.value(), json)
+            .broadcast_create_note(user_id.value(), json, ApVisibility::Public, vec![])
             .await?;
         Ok(())
     }