fix(block2): clearer market states — 'can't reach servers' (retry) vs 'set your area'

Feedback: the market sometimes looked 'disabled'. Now the offline/empty states
are distinct and honest:
- No working relay (defaults exist, so it's a reachability issue) → 'Can't reach
  the community servers right now' + a Retry.
- Online but no area set → 'Set your area' prompt (you'd otherwise see a bare
  'nothing nearby').
- Area set + nothing found → the existing empty state.

i18n en/es/pt; offline tests updated; analyzer clean.

apps/app_seeds/test/ui/market_screen_test.dart

@@ -66,7 +66,7 @@ Widget _wrapMarket(SocialService social, SocialSettings settings,
 }
 
 void main() {
-  testWidgets('offline (no transport) shows the "set up sharing" prompt',
+  testWidgets('offline (no transport) shows the "can\'t reach servers" state',
       (tester) async {
     final cubit = OffersCubit(null);
     addTearDown(cubit.close);
@@ -74,8 +74,8 @@ void main() {
     await tester.pumpWidget(_wrapBody(cubit));
     await tester.pumpAndSettle();
 
-    expect(find.text("Sharing isn't set up yet"), findsOneWidget);
-    expect(find.text('Set up sharing'), findsOneWidget);
+    expect(find.textContaining("Can't reach the community servers"),
+        findsOneWidget);
   });
 
   testWidgets('MarketScreen with no relays configured degrades to offline',
@@ -88,7 +88,7 @@ void main() {
     await tester.pumpAndSettle();
 
     expect(find.text('Seeds near you'), findsOneWidget); // app bar title
-    expect(find.text('Set up sharing'), findsOneWidget); // offline prompt
+    expect(find.text('Retry'), findsOneWidget); // can't-reach state offers retry
   });
 
   testWidgets('"use my location" fills the area with a coarse geohash',