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

.sqlx/query-e6413dcabae4a72628a2abf33a8b65da6f95b7c3c015f2633fcf00c045b9f08b.json

@@ -0,0 +1,68 @@
+{
+  "db_name": "SQLite",
+  "query": "SELECT id, email, username, password_hash, role, bio, avatar_path, banner_path, also_known_as FROM users WHERE id = ?",
+  "describe": {
+    "columns": [
+      {
+        "name": "id",
+        "ordinal": 0,
+        "type_info": "Text"
+      },
+      {
+        "name": "email",
+        "ordinal": 1,
+        "type_info": "Text"
+      },
+      {
+        "name": "username",
+        "ordinal": 2,
+        "type_info": "Text"
+      },
+      {
+        "name": "password_hash",
+        "ordinal": 3,
+        "type_info": "Text"
+      },
+      {
+        "name": "role",
+        "ordinal": 4,
+        "type_info": "Text"
+      },
+      {
+        "name": "bio",
+        "ordinal": 5,
+        "type_info": "Text"
+      },
+      {
+        "name": "avatar_path",
+        "ordinal": 6,
+        "type_info": "Text"
+      },
+      {
+        "name": "banner_path",
+        "ordinal": 7,
+        "type_info": "Text"
+      },
+      {
+        "name": "also_known_as",
+        "ordinal": 8,
+        "type_info": "Text"
+      }
+    ],
+    "parameters": {
+      "Right": 1
+    },
+    "nullable": [
+      true,
+      false,
+      false,
+      false,
+      false,
+      true,
+      true,
+      true,
+      true
+    ]
+  },
+  "hash": "e6413dcabae4a72628a2abf33a8b65da6f95b7c3c015f2633fcf00c045b9f08b"
+}