feat(settings): redesign the Import Key dialog

Rework the full-node Import Key dialog into a safer, Material-consistent, more
capable flow:

- Security: the key is masked by default (Password) with a reveal (eye) toggle,
  a DialogWarningHeader "only import a key you own" note, and the buffer is
  wiped with sodium_memzero on close and on successful import.
- Progress: import triggers a blocking full-chain rescan; the dialog now shows
  "Importing & rescanning — this can take several minutes" with LoadingDots and
  disables Import while it runs (no double-submit). Offline shows a "connect a
  running node" note and disables Import up front.
- Viewing keys: the classifier gains isViewingKey / isRecognizedImportKey;
  importPrivateKey auto-detects a shielded viewing key (zxviews…) and routes to
  z_importviewingkey (watch-only) vs z_importkey / importprivkey. The live type
  indicator shows Transparent / Shielded spending / Shielded viewing (watch-only).
- Result: on success the imported address is captured from the RPC result and
  shown via AddressCopyField.
- Material restyle (OverlayDialogSpec/BlurFloat + TactileButton + Esc) and full
  i18n (12 new keys x 8 languages; CJK subset rebuilt).

Verified: rendered on dark + light skins; a seeded zxviews… key shows the masked
field + "Shielded viewing key (watch-only)" indicator.

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

res/lang/es.json

@@ -416,18 +416,30 @@
     "history": "Historial",
     "immature_type": "Inmaduro",
     "import": "Importar",
+    "import_key_address": "Dirección:",
     "import_key_btn": "Importar Clave(s)",
+    "import_key_done": "Importada. El monedero está reescaneando.",
+    "import_key_field": "Clave",
     "import_key_formats": "Formatos de clave soportados:",
     "import_key_full_rescan": "(0 = re-escaneo completo)",
+    "import_key_import": "Importar",
     "import_key_label": "Clave(s) Privada(s):",
+    "import_key_need_node": "Conecta un nodo en ejecución para importar una clave.",
     "import_key_no_valid": "No se encontraron claves válidas en la entrada",
     "import_key_progress": "Importando %d/%d...",
     "import_key_rescan": "Re-escanear blockchain después de importar",
+    "import_key_rescanning": "Importando y reescaneando: puede tardar varios minutos",
+    "import_key_reveal_tip": "Mostrar/ocultar la clave",
     "import_key_start_height": "Altura inicial:",
     "import_key_success": "Claves importadas exitosamente",
     "import_key_t_format": "Claves privadas WIF de direcciones T",
     "import_key_title": "Importar Clave Privada",
     "import_key_tooltip": "Ingresa una o más claves privadas, una por línea.\nSoporta claves de direcciones z y t.\nLas líneas que empiezan con # se tratan como comentarios.",
+    "import_key_type_tkey": "Clave privada transparente",
+    "import_key_type_unknown": "Formato de clave no reconocido",
+    "import_key_type_zspend": "Clave de gasto blindada",
+    "import_key_type_zview": "Clave de visualización blindada (solo lectura)",
+    "import_key_warn": "Importa solo una clave que te pertenezca: da acceso a sus fondos.",
     "import_key_warning": "Advertencia: ¡Nunca compartas tus claves privadas! Importar claves de fuentes no confiables puede comprometer tu cartera.",
     "import_key_z_format": "Claves de gasto de direcciones Z (secret-extended-key-...)",
     "import_private_key": "Importar Clave Privada...",