fix(wallet-switch): cluster C — no mis-scoping in the unknown-identity window

From the audit: while a switch/first-load is in flight the wallet identity hash
is empty, so contact/portfolio scope-writes silently fell back to "global"
(leaking a wallet-specific entry into every wallet) and scope-filters showed
every wallet's scoped entries.

- Contacts: a NEW wallet-scoped contact created while the identity is unknown is
  now refused with a clear message (tick global or wait); editing an existing
  scoped contact preserves its scope instead of demoting it to global.
- Portfolio: the "Add group" button is disabled while the identity is unknown
  (with a tooltip), so a new group can't get an empty/global scope.
- Both views' visibility filters now show ONLY global entries when the identity
  is unknown — never another wallet's scoped contacts/groups — instead of
  showing everything.
- +2 i18n strings (8 langs; reworded one zh string to stay within the CJK subset).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

res/lang/es.json

@@ -305,6 +305,7 @@
     "contact_global_tt": "Activado: este contacto permanece visible sin importar qué cartera cargues. Desactivado: pertenece solo a la cartera actual.",
     "contact_preview_addr": "La dirección aparecerá aquí",
     "contact_preview_name": "Nombre del contacto",
+    "contact_wallet_loading": "La cartera aún se está cargando: marca «Mostrar en todas las carteras» o inténtalo de nuevo en un momento.",
     "contacts": "Contactos",
     "contacts_search_no_match": "No hay contactos coincidentes",
     "contacts_search_placeholder": "Buscar contactos...",
@@ -977,6 +978,7 @@
     "portfolio_style_featured": "Filas destacadas",
     "portfolio_style_label": "Estilo de cartera",
     "portfolio_untitled": "Sin título",
+    "portfolio_wallet_loading": "Espera a que la cartera termine de cargar para añadir un grupo.",
     "price_chart": "Gráfico de Precios",
     "privacy_great": "¡Excelente privacidad!",
     "privacy_low": "Privacidad baja: protege los fondos",