feat(block2): profiles — your identity card + name/about (NIP-01 kind:0)

Drawer 'Profile' is now live.
- commons_core: ProfileTransport + UserProfile + NostrProfileTransport (kind:0
  publish/fetch), exposed as SocialSession.profile. Round-trip tested against the
  in-process relay (fast dart test).
- app: ProfileStore (local name/about, keystore) + ProfileScreen — shows your
  shareable npub with copy, edits display name + 'about', saves locally and (when
  online) publishes kind:0 so peers can recognise you instead of a raw key.
- Drawer 'Profile' -> /profile (gated like Market/Chat).
- i18n en/es/pt. ProfileStore + profile transport covered by plain/dart tests.

Analyzer clean (both packages).

apps/app_seeds/lib/di/injector.dart

@@ -29,6 +29,7 @@ import '../services/recovery_sheet_service.dart';
 import '../services/share_catalog_service.dart';
 import '../services/message_store.dart';
 import '../services/offer_outbox.dart';
+import '../services/profile_store.dart';
 import '../services/social_service.dart';
 import '../services/social_settings.dart';
 
@@ -92,6 +93,7 @@ Future<void> configureDependencies() async {
     ..registerSingleton<SocialSettings>(SocialSettings(secretStore))
     ..registerSingleton<OfferOutbox>(OfferOutbox(secretStore))
     ..registerSingleton<MessageStore>(MessageStore(secretStore))
+    ..registerSingleton<ProfileStore>(ProfileStore(secretStore))
     ..registerSingleton<ExportImportService>(
       ExportImportService(
         repository: varietyRepository,