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/ui/app_drawer.dart

@@ -45,7 +45,16 @@ class AppDrawer extends StatelessWidget {
                     }
                   : null,
             ),
-            _DrawerItem(icon: const Icon(Icons.person), label: t.menu.profile),
+            _DrawerItem(
+              icon: const Icon(Icons.person),
+              label: t.menu.profile,
+              onTap: marketEnabled
+                  ? () {
+                      Navigator.of(context).pop();
+                      context.go('/profile');
+                    }
+                  : null,
+            ),
             _DrawerItem(
               icon: const Icon(Icons.chat_bubble),
               label: t.menu.chat,