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/test/services/profile_store_test.dart

@@ -0,0 +1,20 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:tane/services/profile_store.dart';
+
+import '../support/test_support.dart';
+
+void main() {
+  late ProfileStore store;
+  setUp(() => store = ProfileStore(InMemorySecretStore()));
+
+  test('defaults are empty', () async {
+    expect(await store.name(), '');
+    expect(await store.about(), '');
+  });
+
+  test('save then read back, trimmed', () async {
+    await store.save(name: '  Alicia  ', about: '  tomate rosa ');
+    expect(await store.name(), 'Alicia');
+    expect(await store.about(), 'tomate rosa');
+  });
+}