fix(lite): require a confirmed 8+ character passphrase to encrypt

The Lite "Encrypt wallet" field and the Create/Restore passphrase had no
confirmation and no minimum length; only an empty passphrase was
refused. Encrypting locks the wallet at once, and a locked wallet cannot
reveal its seed, so a typo there could cost a user without a seed backup
their funds. The full-node encrypt dialog already requires 8 characters
and a confirmation.

This applies to new passphrases only. Opening and unlocking are
unchanged: an existing wallet with a shorter passphrase still opens and
unlocks.

- A pure liteEncryptPassphraseValid(pass, confirm): at least 8 bytes and
  equal to the confirmation. It takes string_views, so the page's secret
  buffers are never copied.
- liteLifecyclePassphraseAcceptable(op, pass, confirm) gates the Settings
  create/open/restore request. Open is never checked, because its
  passphrase field also unlocks an existing wallet. Create and Restore
  are checked only when a passphrase was entered; an empty one still
  creates an unencrypted wallet.
- Encrypt gets a Confirm field. The button stays disabled until the
  passphrase is valid, and a hint says why (too short, with the count,
  or not matching).
- Create/Restore show a Confirm row once a passphrase is typed, with the
  same hint. Validate stays disabled while the passphrase is invalid, so
  a click never wipes a typed seed over a passphrase typo. The request
  builder re-checks the rule.
- The confirmation buffers are wiped with their passphrase: after a run
  or an encrypt, and when the Confirm row is hidden.
- Once the wallet is closed, the Settings page wipes the Encrypt,
  Confirm and Decrypt passphrase buffers whole every time, also when no
  secret was revealed; before, closing the wallet wiped them only while
  clearing a revealed backup or secret. They are zeroed in full because
  an emptied field can still hold the old tail past its first NUL.
- New copy under Encrypt: "Anyone with the wallet file can try
  passphrases offline. Back up your seed phrase first and use a long
  passphrase."
- i18n: three new keys (lite_confirm_label, tt_lite_confirm_pass,
  lite_encrypt_offline_warning) in i18n.cpp and the 8 language files,
  added additively. The hints reuse the wizard's wiz_pass_too_short and
  wiz_pass_mismatch. No new CJK glyphs, so the subset font is unchanged.

Tests: the validator rejects empty, short (7) and mismatched or
unconfirmed passphrases, and accepts 8 or more with a match. The request
gate always accepts Open, even "abc" with no confirmation, accepts
Create/Restore without a passphrase, and applies the rule to them
otherwise. An encrypted, locked wallet still opens and unlocks through
the controller with the 3-character passphrase "abc".

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

res/lang/fr.json

@@ -1008,11 +1008,13 @@
     "lite_birthday_backup": "Date de création : %llu  (à sauvegarder également)",
     "lite_birthday_hint": "Hauteur de bloc à partir de laquelle commencer l'analyse. Laissez 0 si inconnue (analyse complète plus lente).",
     "lite_birthday_label": "Bloc de création",
+    "lite_confirm_label": "Confirmer",
     "lite_console_backend_commands": "Commandes du backend :",
     "lite_console_help_passthrough": "Toute autre entrée est exécutée comme une commande de la console du portefeuille lite.",
     "lite_copy": "Copier",
     "lite_could_not_start": "Impossible de démarrer l'opération",
     "lite_could_not_write": "Impossible d'écrire ",
+    "lite_encrypt_offline_warning": "Toute personne disposant du fichier du portefeuille peut essayer des phrases secrètes hors ligne. Sauvegardez d'abord votre phrase de récupération et utilisez une phrase secrète longue.",
     "lite_encrypt_wallet": "Chiffrer le portefeuille",
     "lite_encryption_removed": "Chiffrement supprimé",
     "lite_enter_all_seed_words": "Entrez les 24 mots de la phrase de récupération (%d obtenus)",
@@ -2059,6 +2061,7 @@
     "tt_keep_daemon": "Le daemon s'arrêtera lors de l'exécution de l'assistant de configuration",
     "tt_language": "Langue de l'interface du portefeuille",
     "tt_layout_hotkey": "Raccourci : touches fléchées gauche/droite pour changer les dispositions de Balance",
+    "tt_lite_confirm_pass": "Saisissez à nouveau la nouvelle phrase secrète ; elle doit correspondre et comporter au moins 8 caractères",
     "tt_lite_copy": "Copie le secret révélé dans le presse-papiers",
     "tt_lite_decrypt_pass": "Saisissez votre phrase de passe pour retirer le chiffrement du portefeuille",
     "tt_lite_encrypt": "Chiffre le portefeuille avec la phrase de passe ci-dessus ; il se verrouille immédiatement et requiert la phrase pour se déverrouiller",