refactor!: CQRS repository split — v0.3.0

FederationRepository (34 methods) → 4 focused traits:
  ActivityRepository  (2)  — idempotency tracking
  FollowRepository    (18) — follower/following graph + migration
  ActorRepository     (6)  — keypairs, remote actor cache, announce tracking
  BlocklistRepository (8)  — domain + actor blocklists

ApObjectHandler (10 methods) → 2 traits:
  ApContentReader  (3) — get_local_objects_for_user/page, count_local_posts
  ApObjectHandler  (9) — all inbox callbacks (on_create, on_mention, etc.)

Builder changes from positional args to named setters:
  ActivityPubService::builder(base_url)
    .activity_repo(arc)
    .follow_repo(arc)
    .actor_repo(arc)
    .blocklist_repo(arc)
    .user_repo(arc)
    .content_reader(arc)
    .object_handler(arc)
    .build()

No behaviour changes.

src/repository/follow.rs

@@ -0,0 +1,97 @@
+use anyhow::Result;
+use async_trait::async_trait;
+
+use super::{Follower, FollowerStatus, FollowingStatus, RemoteActor};
+
+/// Manages follower/following relationships and account migration.
+#[async_trait]
+pub trait FollowRepository: Send + Sync {
+    // ── Inbound followers ───────────────────────────────────────────────────
+    async fn add_follower(
+        &self,
+        local_user_id: uuid::Uuid,
+        remote_actor_url: &str,
+        status: FollowerStatus,
+        follow_activity_id: &str,
+    ) -> Result<()>;
+    async fn get_follower_follow_activity_id(
+        &self,
+        local_user_id: uuid::Uuid,
+        remote_actor_url: &str,
+    ) -> Result<Option<String>>;
+    async fn remove_follower(
+        &self,
+        local_user_id: uuid::Uuid,
+        remote_actor_url: &str,
+    ) -> Result<()>;
+    async fn get_followers(&self, local_user_id: uuid::Uuid) -> Result<Vec<Follower>>;
+    async fn get_followers_page(
+        &self,
+        local_user_id: uuid::Uuid,
+        offset: u32,
+        limit: usize,
+    ) -> Result<Vec<Follower>>;
+    async fn count_followers(&self, local_user_id: uuid::Uuid) -> Result<usize>;
+    async fn update_follower_status(
+        &self,
+        local_user_id: uuid::Uuid,
+        remote_actor_url: &str,
+        status: FollowerStatus,
+    ) -> Result<()>;
+    async fn get_pending_followers(
+        &self,
+        local_user_id: uuid::Uuid,
+    ) -> Result<Vec<RemoteActor>>;
+    /// Return deduplicated inbox URLs (shared_inbox preferred) for accepted
+    /// followers, excluding blocked actors/domains. DB-side filtering.
+    async fn get_accepted_follower_inboxes(
+        &self,
+        local_user_id: uuid::Uuid,
+    ) -> Result<Vec<String>>;
+
+    // ── Outbound following ──────────────────────────────────────────────────
+    async fn add_following(
+        &self,
+        local_user_id: uuid::Uuid,
+        actor: RemoteActor,
+        follow_activity_id: &str,
+    ) -> Result<()>;
+    async fn get_follow_activity_id(
+        &self,
+        local_user_id: uuid::Uuid,
+        remote_actor_url: &str,
+    ) -> Result<Option<String>>;
+    async fn remove_following(
+        &self,
+        local_user_id: uuid::Uuid,
+        actor_url: &str,
+    ) -> Result<()>;
+    async fn get_following(&self, local_user_id: uuid::Uuid) -> Result<Vec<RemoteActor>>;
+    async fn get_following_page(
+        &self,
+        local_user_id: uuid::Uuid,
+        offset: u32,
+        limit: usize,
+    ) -> Result<Vec<RemoteActor>>;
+    async fn count_following(&self, local_user_id: uuid::Uuid) -> Result<usize>;
+    async fn update_following_status(
+        &self,
+        local_user_id: uuid::Uuid,
+        remote_actor_url: &str,
+        status: FollowingStatus,
+    ) -> Result<()>;
+    async fn get_following_outbox_url(
+        &self,
+        local_user_id: uuid::Uuid,
+        remote_actor_url: &str,
+    ) -> Result<Option<String>>;
+
+    // ── Account migration ───────────────────────────────────────────────────
+    /// Migrate all follower records from `old_actor_url` to `new_actor_url`.
+    /// Returns local user IDs that need a re-follow sent.
+    async fn migrate_follower_actor(
+        &self,
+        old_actor_url: &str,
+        new_actor_url: &str,
+    ) -> Result<Vec<uuid::Uuid>>;
+}