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/de.json

@@ -1008,11 +1008,13 @@
     "lite_birthday_backup": "Geburtstag: %llu  (auch diesen sichern)",
     "lite_birthday_hint": "Blockhöhe, ab der gescannt werden soll. Bei 0 belassen, falls unbekannt (langsamerer vollständiger Scan).",
     "lite_birthday_label": "Geburtsblock",
+    "lite_confirm_label": "Bestätigen",
     "lite_console_backend_commands": "Backend-Befehle:",
     "lite_console_help_passthrough": "Jede andere Eingabe wird als Lite-Wallet-Konsolenbefehl ausgeführt.",
     "lite_copy": "Kopieren",
     "lite_could_not_start": "Der Vorgang konnte nicht gestartet werden",
     "lite_could_not_write": "Konnte nicht schreiben ",
+    "lite_encrypt_offline_warning": "Wer die Wallet-Datei hat, kann Passphrasen offline durchprobieren. Sichern Sie zuerst Ihre Wiederherstellungsphrase und verwenden Sie eine lange Passphrase.",
     "lite_encrypt_wallet": "Wallet verschlüsseln",
     "lite_encryption_removed": "Verschlüsselung entfernt",
     "lite_enter_all_seed_words": "Alle 24 Seed-Wörter zur Wiederherstellung eingeben (%d erhalten)",
@@ -2059,6 +2061,7 @@
     "tt_keep_daemon": "Der Daemon wird beim Ausführen des Einrichtungsassistenten gestoppt",
     "tt_language": "Schnittstellensprache der Wallet-UI",
     "tt_layout_hotkey": "Hotkey: Links-/Rechts-Pfeiltasten zum Wechseln der Balance-Layouts",
+    "tt_lite_confirm_pass": "Geben Sie die neue Passphrase erneut ein; sie muss übereinstimmen und mindestens 8 Zeichen lang sein",
     "tt_lite_copy": "Das angezeigte Geheimnis in die Zwischenablage kopieren",
     "tt_lite_decrypt_pass": "Gib deine Passphrase ein, um die Verschlüsselung von der Wallet zu entfernen",
     "tt_lite_encrypt": "Die Wallet mit der obigen Passphrase verschlüsseln; sie wird sofort gesperrt und benötigt die Passphrase zum Entsperren",