feat(device-sync): manifest, cancel, font picker + sync status fix

- Write psysonic-sync.json to device after sync/deletions; auto-import
  on folder select when localStorage is empty (cross-platform handoff)
- Add cancel button during active sync: AtomicBool flag per job,
  tasks bail after acquiring semaphore, cancelled state in UI
- Fix sync status staying "pending": normalize template path separators
  to OS separator (Windows: '/' → '\') so compute_sync_paths and
  list_device_dir_files produce matching strings for Set comparison
- Add Geist and JetBrains Mono as variable fonts; font picker collapsible
- Fix device mount detection on Windows: removable drive letters (E:\)
  were incorrectly skipped alongside system roots; strip \?\ prefix
  from canonicalized paths before mount-point comparison

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/locales/es.ts

@@ -1103,6 +1103,8 @@ export const esTranslation = {
     fetchError: 'Error al obtener pistas del servidor.',
     syncComplete: 'Sincronización completada.',
     dismiss: 'Cerrar',
+    cancelSync: 'Cancelar',
+    syncCancelled: 'Sincronización cancelada ({{done}} / {{total}} transferidos).',
     colName: 'Nombre',
     colType: 'Tipo',
     colStatus: 'Estado',
@@ -1112,6 +1114,7 @@ export const esTranslation = {
     deleteFromDevice: 'Marcar para eliminar ({{count}})',
     confirmDelete: '¿Eliminar {{count}} elemento(s) del dispositivo: {{names}}?',
     deleteComplete: '{{count}} elemento(s) eliminado(s) del dispositivo.',
+    manifestImported: '{{count}} fuente(s) importada(s) desde el manifiesto del dispositivo.',
     statusSynced: 'Sincronizado',
     statusPending: 'Pendiente',
     statusDeletion: 'Eliminación',