fix(app): accept incoming calls, restore from recovery phrase, duress session isolation, message loss

Calls: `call` was missing from the known content types, so every offer was
acknowledged and dropped; the call screen column now fills the width (the
avatar jumped left after hang-up); a ring started from a push ends after
12 s when no offer arrives; STUN fallback when no TURN credentials.
Registration: X-Sepot-Identity-Proof lets a new device reclaim an existing
identity; retry backs off from 30 s to 10 min and exposes a conflict flag.
Prekeys: PrekeysLow triggers a batch of 50 one-time prekeys via POST
/v1/keys; the signed prekey rotates weekly, the Kyber prekey monthly.
Messaging: crypto operations run serially (concurrent encrypts derived the
same message key); stop() waits for in-flight deliveries (auto-lock between
decrypt and persist lost messages); disappearing-message cleanup no longer
overwrites fresh messages; a push wake-up reconnects stale connections; the
outbox carries polls and mentions; length limits on wire input.
Storage: a duress session never exposes the real identity or phrase, does
not start networking and cannot touch the keystore; deleting data in a
duress session leaves the real account alone; PIN guessing is throttled
(5 misses, then 30 s doubling up to 15 min); the duress blob shares the salt
so unlock time does not reveal which PIN was entered; iOS keychain items are
this-device only; biometrics are biometric-only; screen security defaults
to on and is applied after unlock; tapjacking filter in MainActivity.
Tests: content types, shared-salt unwrap, duress isolation.

app/lib/l10n/generated/app_localizations.dart

@@ -1994,6 +1994,12 @@ abstract class AppLocalizations {
   /// **'Chyba odemčení'**
   String get pinUnlockError;
 
+  /// Hláška na odemykací obrazovce po sérii špatných PINů; {seconds} = počet sekund do dalšího pokusu
+  ///
+  /// In cs, this message translates to:
+  /// **'Příliš mnoho pokusů. Zkus to za {seconds} s.'**
+  String pinLockedFor(int seconds);
+
   /// Titulek SimpleDialog výběru režimu pushů. Stejný text jako title ListTile v nastavení (ř. 184) → stejný klíč. | Title ListTile v nastavení — stejný text a klíč jako titulek dialogu (ř. 44)
   ///
   /// In cs, this message translates to:

app/lib/l10n/generated/app_localizations_cs.dart

@@ -1102,6 +1102,11 @@ class AppLocalizationsCs extends AppLocalizations {
   @override
   String get pinUnlockError => 'Chyba odemčení';
 
+  @override
+  String pinLockedFor(int seconds) {
+    return 'Příliš mnoho pokusů. Zkus to za $seconds s.';
+  }
+
   @override
   String get pushTitle => 'Push notifikace';
 

app/lib/l10n/generated/app_localizations_de.dart

@@ -1121,6 +1121,11 @@ class AppLocalizationsDe extends AppLocalizations {
   @override
   String get pinUnlockError => 'Fehler beim Entsperren';
 
+  @override
+  String pinLockedFor(int seconds) {
+    return 'Zu viele Versuche. Versuche es in $seconds s erneut.';
+  }
+
   @override
   String get pushTitle => 'Push-Benachrichtigungen';
 

app/lib/l10n/generated/app_localizations_en.dart

@@ -1101,6 +1101,11 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get pinUnlockError => 'Unlock error';
 
+  @override
+  String pinLockedFor(int seconds) {
+    return 'Too many attempts. Try again in $seconds s.';
+  }
+
   @override
   String get pushTitle => 'Push notifications';
 

app/lib/l10n/generated/app_localizations_it.dart

@@ -1111,6 +1111,11 @@ class AppLocalizationsIt extends AppLocalizations {
   @override
   String get pinUnlockError => 'Errore di sblocco';
 
+  @override
+  String pinLockedFor(int seconds) {
+    return 'Troppi tentativi. Riprova tra $seconds s.';
+  }
+
   @override
   String get pushTitle => 'Notifiche push';
 

app/lib/l10n/generated/app_localizations_ru.dart

@@ -1118,6 +1118,11 @@ class AppLocalizationsRu extends AppLocalizations {
   @override
   String get pinUnlockError => 'Ошибка разблокировки';
 
+  @override
+  String pinLockedFor(int seconds) {
+    return 'Слишком много попыток. Повторите через $seconds с.';
+  }
+
   @override
   String get pushTitle => 'Push-уведомления';