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/main.dart

@@ -10,6 +10,7 @@ import 'services/coarse_location.dart';
 import 'services/message_store.dart';
 import 'services/offer_outbox.dart';
 import 'services/onboarding_store.dart';
+import 'services/profile_store.dart';
 import 'services/social_service.dart';
 import 'services/social_settings.dart';
 
@@ -29,6 +30,7 @@ Future<void> main() async {
         location: const GeolocatorCoarseLocation(),
         outbox: getIt<OfferOutbox>(),
         messageStore: getIt<MessageStore>(),
+        profileStore: getIt<ProfileStore>(),
         showIntro: !await onboarding.introSeen(),
         autoBackup: getIt.isRegistered<AutoBackupService>()
             ? getIt<AutoBackupService>()