feat(ap): ActivityPub spec compliance and profile completeness

Phase 1 — spec compliance:
- Add AS_PUBLIC constant; add to/cc fields to CreateActivity, DeleteActivity,
  UpdateActivity, AddActivity; populate on all broadcast call sites
- Add @context to outbox CreateActivity items
- Set manuallyApprovesFollowers: true to match actual Pending follow flow
- Gate PermissiveVerifier behind FEDERATION_DEBUG env var
- Add updated timestamp to Person actor JSON
- Improve actor update delivery logging

Phase 2a Batch 1 — AP layer:
- Add /inbox shared inbox route; add endpoints.sharedInbox to Person
- Paginate followers and following collections (20/page, OrderedCollectionPage)

Phase 2a Batch 2 — profile completeness:
- DB migrations: banner_path, also_known_as columns; user_profile_fields table
- ProfileField value object; UserProfileFieldsRepository port
- Banner image upload (stored via image-converter, surfaced as image in Person)
- alsoKnownAs field in Person (account migration support)
- Custom profile fields (up to 4 PropertyValue attachments in Person)
- Profile settings UI: banner preview/upload, alsoKnownAs input, fields form
- PUT /api/v1/profile/fields API endpoint

crates/application/src/context.rs

@@ -6,7 +6,7 @@ use domain::ports::{
     ImportProfileRepository, ImportSessionRepository,
     MetadataClient, MovieProfileRepository, MovieRepository, PasswordHasher, PosterFetcherClient,
     PersonCommand, PersonQuery, SearchCommand, SearchPort,
-    ReviewRepository, StatsRepository, UserRepository,
+    ReviewRepository, StatsRepository, UserProfileFieldsRepository, UserRepository,
     WatchlistRepository,
 };
 #[cfg(feature = "federation")]
@@ -37,6 +37,7 @@ pub struct AppContext {
     pub search_port: Arc<dyn SearchPort>,
     pub search_command: Arc<dyn SearchCommand>,
     pub watchlist_repository: Arc<dyn WatchlistRepository>,
+    pub profile_fields_repository: Arc<dyn UserProfileFieldsRepository>,
     #[cfg(feature = "federation")]
     pub remote_watchlist_repository: Arc<dyn RemoteWatchlistRepository>,
     pub config: AppConfig,