v0.5.0 — codebase refinement, flexible API, architecture cleanup

Error handling:
  thiserror enum (NotFound/BadRequest/Unauthorized/Forbidden/Internal)
  eliminates 41 boilerplate .map_err() calls
  signature failures return 401, not 500

Named types:
  Keypair, LocalObject (with to/cc/bto/bcc addressing), Addressing

Readability:
  descriptive names everywhere, small functions, breathing room
  noisy comments removed, intent-explicit error handling (no let _ =)
  types.rs per module separating data from behavior

File organization:
  handlers/ module (actor, featured, followers, inbox, nodeinfo, outbox, webfinger)
  actors/ split (mod.rs + person.rs + types.rs)
  service/ split (builder, broadcast, collections, delivery, fetch, follow, lookup, types)
  tests next to modules

Repository traits:
  FollowRepository → 5 sub-traits (FollowerWriter/Reader, FollowingWriter/Reader, FollowMigration)
  ActorRepository → 3 sub-traits (KeypairRepository, RemoteActorCache, AnnounceRepository)
  BlocklistRepository → 2 sub-traits (DomainBlocklist, ActorBlocklist)
  supertraits with blanket impls — existing consumers unchanged
  FollowMigration has default no-op
  delete dead get_following_outbox_url

Testing:
  mock_repo! macro generates mock builders from compact specs
  MockFollowRepo, MockActorRepo, MockBlocklistRepo, MockActivityRepo,
  MockUserRepo, MockContentReader, MockObjectHandler, MockEventPublisher
  all hand-written test stubs replaced

Flexibility:
  UrlScheme trait — configurable URL patterns (DefaultUrlScheme = /users/{uuid})
  on_unknown_activity hook for custom AP extensions
  broadcast_raw_to_followers for arbitrary activity JSON
  broadcast_create/broadcast_update (renamed from Note-centric names)
  internal modules locked to pub(crate), clean public re-exports
  actor_handler, followers_handler, following_handler re-exported for custom routers

Security:
  SSRF: block IPv6-mapped private IPv4, TEST-NET, benchmarking, reserved ranges
  verify_attributed_to rejects missing/array attributedTo
  remove .expect() from outbox handler

Architecture:
  handlers/followers.rs delegates to serialize_ordered_collection (no more UrlScheme bypass)
  extract dispatch_sends, prepare_addressed_broadcast (eliminate duplication)
  DbActor::object_id(), RemoteActor::from/from_ap_person/placeholder
  send_activity unifies prepare+dispatch, deterministic_activity_id helper
  pass-through wrappers grouped in lookup.rs

src/handlers/actor.rs

@@ -0,0 +1,24 @@
+use activitypub_federation::{
+    axum::json::FederationJson, config::Data, protocol::context::WithContext, traits::Object,
+};
+use axum::extract::Path;
+
+use crate::actors::{Person, get_local_actor};
+use crate::data::FederationData;
+use crate::error::Error;
+use crate::urls::actor_ap_context;
+
+/// Serves the AP actor JSON for a local user.
+/// The path parameter is the user's UUID (matching the canonical actor URL).
+pub async fn actor_handler(
+    Path(user_id_str): Path<String>,
+    data: Data<FederationData>,
+) -> Result<FederationJson<WithContext<Person>>, Error> {
+    let user_id =
+        uuid::Uuid::parse_str(&user_id_str).map_err(|_| Error::not_found("user not found"))?;
+
+    let db_actor = get_local_actor(user_id, &data).await?;
+    let person = db_actor.into_json(&data).await?;
+
+    Ok(FederationJson(WithContext::new(person, actor_ap_context())))
+}