feat: image storage generalization, user profile, and federation polish

- Replace PosterStorage with generic ImageStorage port (IMAGE_STORAGE_BACKEND/PATH env vars)
- Rename poster-storage crate to image-storage; serve at /images/{*key}
- Add bio and avatar_path to User model (migration 0009_user_profile)
- update_profile use case with avatar upload, mime validation, old avatar cleanup
- GET/PUT /api/v1/profile and GET/POST /settings/profile HTML page
- Enrich AP Person actor with summary, icon, url, discoverable fields
- Store remote actor avatar_url (migration 0010_ap_remote_actor_avatar)
- Shared inbox delivery via collect_inboxes deduplication
- Broadcast Update(Person) to followers on UserUpdated event
- Paginated outbox: OrderedCollection + OrderedCollectionPage with cursor
- Announce/boost tracking in ap_announces table (migration 0011_ap_announces)

crates/adapters/postgres/migrations/0009_user_profile.sql

@@ -0,0 +1,2 @@
+ALTER TABLE users ADD COLUMN bio TEXT;
+ALTER TABLE users ADD COLUMN avatar_path TEXT;

crates/adapters/postgres/migrations/0010_ap_remote_actor_avatar.sql

@@ -0,0 +1 @@
+ALTER TABLE ap_remote_actors ADD COLUMN avatar_url TEXT;

crates/adapters/postgres/migrations/0011_ap_announces.sql

@@ -0,0 +1,8 @@
+CREATE TABLE ap_announces (
+    id           TEXT PRIMARY KEY,
+    object_url   TEXT NOT NULL,
+    actor_url    TEXT NOT NULL,
+    announced_at TEXT NOT NULL
+);
+
+CREATE INDEX idx_ap_announces_object ON ap_announces (object_url);