fix(app): say it out loud when wake-ups do not work

Registration failures from the distributor were swallowed, so push looked
enabled while nothing arrived. Without wake-ups Android suspends the app
and messages only show up once the user opens it — which looks like broken
delivery even though the relay has them queued.

The failure is now remembered and surfaced in Settings, and the chat list
carries a dismissible line explaining the state.

app/lib/l10n/generated/app_localizations_cs.dart

@@ -961,6 +961,18 @@ class AppLocalizationsCs extends AppLocalizations {
     return 'Nastavení pushů selhalo: $error';
   }
 
+  @override
+  String get pushHintOff =>
+      'Zprávy ti přijdou, až Šepot otevřeš — budíčky nejsou nastavené.';
+
+  @override
+  String get pushHintFailed =>
+      'Budíčky nefungují, zprávy uvidíš až po otevření Šepotu.';
+
+  @override
+  String get pushRegistrationFailed =>
+      'Budíčky nechodí — distributor registraci odmítl. Zkus push vypnout a znovu zapnout.';
+
   @override
   String get pushNoDistributorTitle => 'Žádný distributor';