feat(apple): saved devices and targeted transfers UI

Adds the native SwiftUI Saved Devices experience on top of the production
saved-device core, as a top-level destination in the iOS tab bar and the
macOS sidebar.

Core seam:
- App-facing saved-device domain models mirroring core/SavedDeviceModels.kt,
  with lifecycle helpers (canReceive/canResume/canCancel/canDelete) so views
  never hand-roll state checks.
- 21 gateway methods through CoreGateway/CoreRepository with UniFFI mapping.
  cancelTargetedTransfer, forgetSavedDevice and blockDevice run off the serial
  lane: each must reach the core while a targeted receive is blocking it.
- Payload-free pairingChanged/targetedTransferChanged signals, dispatched
  before the numeric-transferId guard since saved-device events identify
  their subject by peer endpoint or a string transfer id.

Experience:
- Screen lists saved devices and outstanding consent requests only; the
  global targeted-transfer history stays out, reachable per device.
- Details as a sheet with detents on compact layouts and a native inspector
  on macOS, owning Send, label, forget/block and that device's transfers.
- Label editing is transactional: the draft and editor survive a failed
  write, conflicting actions are refused while saving, and the editor closes
  only after the core confirms.
- Pairing and targeted-offer consent hosted at the app root, answerable from
  any tab and suppressed while a transfer approval is up. Dismissing a
  pairing prompt suppresses locally without consuming the single-use
  eligibility; dismissing an offer declines it, since an unanswered offer
  holds a slot in the core's bounded per-sender queue.
- Targeted send reuses the invitation composer's affordances with file,
  folder, rename, replace and cleanup parity. Picker copies are released on
  replace/remove/clear/cancel and after a successful create, but kept after a
  failure so retry does not require re-picking.
- Notifications for pairing requests and offers (withdrawn once answered) and
  for terminal targeted transfers. Wording follows direction: on the sending
  device the peer finished receiving, not us.

Localization:
- Widens 52 saved-device keys from kmp-only to both platforms.
- Five keys carried a literal %1$s with no declared args, which Compose
  renders positionally but the Apple generator emits as a plain constant,
  leaking the placeholder into the UI. They now use named args; Compose
  output is byte-identical.
- Adds targeted_offer_title/body. Reusing the invitation approval copy stated
  the roles backwards, announcing the sender as the receiver.

Also surfaces core startup failures: the startup overlay is drawn above the
snackbar host, so a failed initialize() was indistinguishable from an app
that never finished loading. AppModel now keeps the reason, logs it, and the
overlay shows it with a retry, plus the technical detail in DEBUG builds.

Send and receive between two devices is verified only partially; a missing
endpoint-identity credential currently blocks startup on the test device.

shared/src/commonMain/composeResources/values-de/strings.xml

@@ -265,6 +265,8 @@
     <string name="storage_total">Gesamt</string>
     <string name="storage_transfer_data">Übertragungsdaten</string>
     <string name="storage_transfers_deleted">Alle Übertragungen gelöscht</string>
+    <string name="targeted_offer_body">%1$s möchte Ihnen „%2$s“ senden.</string>
+    <string name="targeted_offer_title">Eingehende Übertragung</string>
     <string name="transfer_activity_description">Wichtige Aktualisierungen zu dieser Übertragung ansehen</string>
     <string name="transfer_activity_title">Aktivität</string>
     <string name="transfer_delete_description">„%1$s“ wird nicht mehr geteilt und sein Übertragungsverlauf wird von diesem Gerät entfernt.</string>

shared/src/commonMain/composeResources/values-es/strings.xml

@@ -265,6 +265,8 @@
     <string name="storage_total">Total</string>
     <string name="storage_transfer_data">Datos de transferencia</string>
     <string name="storage_transfers_deleted">Todas las transferencias eliminadas</string>
+    <string name="targeted_offer_body">%1$s quiere enviarle “%2$s”.</string>
+    <string name="targeted_offer_title">Transferencia entrante</string>
     <string name="transfer_activity_description">Vea las actualizaciones importantes de esta transferencia</string>
     <string name="transfer_activity_title">Actividad</string>
     <string name="transfer_delete_description">«%1$s» dejará de compartirse y su historial de transferencia se eliminará de este dispositivo.</string>

shared/src/commonMain/composeResources/values-fr/strings.xml

@@ -265,6 +265,8 @@
     <string name="storage_total">Total</string>
     <string name="storage_transfer_data">Données de transfert</string>
     <string name="storage_transfers_deleted">Tous les transferts supprimés</string>
+    <string name="targeted_offer_body">%1$s veut vous envoyer « %2$s ».</string>
+    <string name="targeted_offer_title">Transfert entrant</string>
     <string name="transfer_activity_description">Consultez les mises à jour importantes de ce transfert</string>
     <string name="transfer_activity_title">Activité</string>
     <string name="transfer_delete_description">« %1$s » cessera d’être partagé et son historique de transfert sera retiré de cet appareil.</string>

shared/src/commonMain/composeResources/values-it/strings.xml

@@ -265,6 +265,8 @@
     <string name="storage_total">Totale</string>
     <string name="storage_transfer_data">Dati di trasferimento</string>
     <string name="storage_transfers_deleted">Tutti i trasferimenti eliminati</string>
+    <string name="targeted_offer_body">%1$s vuole inviarle “%2$s”.</string>
+    <string name="targeted_offer_title">Trasferimento in arrivo</string>
     <string name="transfer_activity_description">Veda gli aggiornamenti importanti di questo trasferimento</string>
     <string name="transfer_activity_title">Attività</string>
     <string name="transfer_delete_description">«%1$s» non verrà più condiviso e la sua cronologia di trasferimento verrà rimossa da questo dispositivo.</string>

shared/src/commonMain/composeResources/values-nl/strings.xml

@@ -265,6 +265,8 @@
     <string name="storage_total">Totaal</string>
     <string name="storage_transfer_data">Overdrachtsgegevens</string>
     <string name="storage_transfers_deleted">Alle overdrachten verwijderd</string>
+    <string name="targeted_offer_body">%1$s wil u “%2$s” sturen.</string>
+    <string name="targeted_offer_title">Inkomende overdracht</string>
     <string name="transfer_activity_description">Bekijk belangrijke updates voor deze overdracht</string>
     <string name="transfer_activity_title">Activiteit</string>
     <string name="transfer_delete_description">‘%1$s’ wordt niet meer gedeeld en de overdrachtsgeschiedenis wordt van dit apparaat verwijderd.</string>

shared/src/commonMain/composeResources/values-pl/strings.xml

@@ -265,6 +265,8 @@
     <string name="storage_total">Łącznie</string>
     <string name="storage_transfer_data">Dane transferu</string>
     <string name="storage_transfers_deleted">Usunięto wszystkie transfery</string>
+    <string name="targeted_offer_body">%1$s chce wysłać Ci „%2$s”.</string>
+    <string name="targeted_offer_title">Transfer przychodzący</string>
     <string name="transfer_activity_description">Zobacz ważne aktualizacje tego transferu</string>
     <string name="transfer_activity_title">Aktywność</string>
     <string name="transfer_delete_description">„%1$s” przestanie być udostępniany, a jego historia transferu zostanie usunięta z tego urządzenia.</string>

shared/src/commonMain/composeResources/values-pt/strings.xml

@@ -265,6 +265,8 @@
     <string name="storage_total">Total</string>
     <string name="storage_transfer_data">Dados de transferência</string>
     <string name="storage_transfers_deleted">Todas as transferências eliminadas</string>
+    <string name="targeted_offer_body">%1$s quer enviar-lhe “%2$s”.</string>
+    <string name="targeted_offer_title">Transferência a receber</string>
     <string name="transfer_activity_description">Ver as atualizações importantes desta transferência</string>
     <string name="transfer_activity_title">Atividade</string>
     <string name="transfer_delete_description">«%1$s» deixará de ser partilhado e o seu histórico de transferência será removido deste dispositivo.</string>

shared/src/commonMain/composeResources/values-ru/strings.xml

@@ -265,6 +265,8 @@
     <string name="storage_total">Всего</string>
     <string name="storage_transfer_data">Данные передачи</string>
     <string name="storage_transfers_deleted">Все передачи удалены</string>
+    <string name="targeted_offer_body">%1$s хочет отправить вам «%2$s».</string>
+    <string name="targeted_offer_title">Входящая передача</string>
     <string name="transfer_activity_description">Просматривайте важные обновления этой передачи</string>
     <string name="transfer_activity_title">Активность</string>
     <string name="transfer_delete_description">Общий доступ к «%1$s» будет остановлен, а история передачи будет удалена с этого устройства.</string>

shared/src/commonMain/composeResources/values/strings.xml

@@ -265,6 +265,8 @@
     <string name="storage_total">Total</string>
     <string name="storage_transfer_data">Transfer data</string>
     <string name="storage_transfers_deleted">All transfers deleted</string>
+    <string name="targeted_offer_body">%1$s wants to send you “%2$s”.</string>
+    <string name="targeted_offer_title">Incoming transfer</string>
     <string name="transfer_activity_description">See important updates for this transfer</string>
     <string name="transfer_activity_title">Activity</string>
     <string name="transfer_delete_description">“%1$s” will stop being shared and its transfer history will be removed from this device.</string>