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

CHANGELOG.md

@@ -1,5 +1,51 @@
 # Changelog
 
+## [0.5.0] — 2026-07-25
+
+### Breaking changes
+
+- `broadcast_create_note` renamed to `broadcast_create`, `broadcast_update_note` renamed to `broadcast_update`
+- `LocalObject` is now a named struct with addressing fields: `to`, `cc`, `bto`, `bcc`
+- `ApContentReader::get_local_objects_page` returns `Vec<LocalObject>` instead of `Vec<(Url, Value, DateTime)>`
+- `Error` is now a thiserror enum with `NotFound` / `BadRequest` / `Unauthorized` / `Forbidden` / `Internal` variants
+- Repository traits split into sub-traits — `FollowRepository` is now a supertrait of `FollowerWriter`, `FollowerReader`, `FollowingWriter`, `FollowingReader`, `FollowMigration`; `ActorRepository` is a supertrait of `KeypairRepository`, `RemoteActorCache`, `AnnounceRepository`. Existing consumers implementing the supertrait continue to work unchanged.
+- `ActorRepository::save_local_actor_keypair` now takes a `Keypair` named struct instead of two strings
+- `NoteType` re-export removed
+- Internal modules (`activities`, `actors`, `handlers`, `data`, `content`, `error`, `user`, `federation`) are now `pub(crate)`
+- `get_following_outbox_url` removed (dead code)
+
+### New features
+
+- `UrlScheme` trait + `DefaultUrlScheme` — configurable URL patterns via `.url_scheme(Arc::new(MyScheme))` on the builder
+- `broadcast_raw_to_followers` — send arbitrary AP activity JSON to all accepted followers
+- `on_unknown_activity` hook on `ApObjectHandler` — handle custom AP extensions (EmojiReact, Question, Flag, etc.)
+- `DbActor::object_id()` convenience method
+- `RemoteActor::from_ap_person()`, `RemoteActor::placeholder()` constructors
+- Mock builder framework: `MockFollowRepoBuilder`, `MockActorRepoBuilder`, `MockBlocklistRepoBuilder`, `MockActivityRepoBuilder`, `MockUserRepoBuilder`, `MockContentReaderBuilder`, `MockObjectHandlerBuilder`, `MockEventPublisherBuilder`
+- `Keypair` named struct (was anonymous tuple)
+- `LocalObject` named struct with addressing (was anonymous tuple)
+- `FollowMigration::migrate_follower_actor` has a default no-op implementation
+- `actor_handler`, `followers_handler`, `following_handler` re-exported for custom router construction
+- Constants: `AP_CONTENT_TYPE`, `AP_CONTEXT`, `INBOX_BODY_LIMIT`
+
+### Bug fixes / security
+
+- Fix SSRF bypass via IPv6-mapped IPv4 addresses
+- Block additional reserved IP ranges (TEST-NET, benchmarking, reserved, IPv6 documentation)
+- `verify_attributed_to` now rejects missing `attributedTo` and handles array form
+- Signature failures return 401 instead of 500
+- Remove `.expect()` panics from outbox handler
+- Unknown activity types accepted gracefully instead of returning 500
+
+### Internal improvements
+
+- thiserror enum for `Error` type (41 boilerplate `.map_err` calls eliminated)
+- File organization: `handlers/`, `actors/`, `service/` with `types.rs` per module
+- `mock_repo!` macro replaces 980 lines of hand-written mocks
+- Small focused functions and descriptive variable names throughout
+
+---
+
 ## [0.4.6] — 2026-07-16
 
 ### New features