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/adapters/template-askama/src/lib.rs

@@ -342,6 +342,9 @@ struct ProfileSettingsTemplate<'a> {
     ctx: &'a HtmlPageContext,
     bio: Option<&'a str>,
     avatar_url: Option<&'a str>,
+    banner_url: Option<&'a str>,
+    also_known_as: Option<&'a str>,
+    profile_fields: &'a [(String, String)],
     saved: bool,
 }
 
@@ -703,6 +706,9 @@ impl HtmlRenderer for AskamaHtmlRenderer {
             ctx: &data.ctx,
             bio: data.bio.as_deref(),
             avatar_url: data.avatar_url.as_deref(),
+            banner_url: data.banner_url.as_deref(),
+            also_known_as: data.also_known_as.as_deref(),
+            profile_fields: &data.profile_fields,
             saved: data.saved,
         }
         .render()