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/pt.json

@@ -305,6 +305,7 @@
     "contact_global_tt": "Ativado: este contato permanece visível em qualquer carteira que você carregar. Desativado: ele pertence apenas à carteira atual.",
     "contact_preview_addr": "O endereço aparecerá aqui",
     "contact_preview_name": "Nome do contato",
+    "contact_wallet_loading": "A carteira ainda está carregando — marque “Mostrar em todas as carteiras” ou tente novamente em um momento.",
     "contacts": "Contatos",
     "contacts_search_no_match": "Nenhum contato correspondente",
     "contacts_search_placeholder": "Pesquisar contatos...",
@@ -977,6 +978,7 @@
     "portfolio_style_featured": "Linhas em destaque",
     "portfolio_style_label": "Estilo do portfólio",
     "portfolio_untitled": "Sem título",
+    "portfolio_wallet_loading": "Aguarde a carteira terminar de carregar para adicionar um grupo.",
     "price_chart": "Gráfico de Preços",
     "privacy_great": "Ótima privacidade!",
     "privacy_low": "Baixa privacidade — blinde os fundos",