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/zh.json

@@ -1008,11 +1008,13 @@
     "lite_birthday_backup": "生日区块：%llu （也请一并备份）",
     "lite_birthday_hint": "开始扫描的区块高度。如未知请保留 0（完整扫描更慢）。",
     "lite_birthday_label": "诞生区块",
+    "lite_confirm_label": "确认",
     "lite_console_backend_commands": "后端命令：",
     "lite_console_help_passthrough": "其他任何输入都将作为轻钱包控制台命令运行。",
     "lite_copy": "复制",
     "lite_could_not_start": "无法启动该操作",
     "lite_could_not_write": "无法写入 ",
+    "lite_encrypt_offline_warning": "任何拿到钱包文件的人都可以离线尝试密码。请先备份助记词，并使用较长的密码短语。",
     "lite_encrypt_wallet": "加密钱包",
     "lite_encryption_removed": "已移除加密",
     "lite_enter_all_seed_words": "请输入全部 24 个助记词以恢复（已输入 %d 个）",
@@ -2059,6 +2061,7 @@
     "tt_keep_daemon": "运行设置向导时守护进程仍会停止",
     "tt_language": "钱包界面语言",
     "tt_layout_hotkey": "快捷键：左/右箭头键切换余额布局",
+    "tt_lite_confirm_pass": "再次输入新的密码短语；两次输入必须一致，且至少 8 个字符",
     "tt_lite_copy": "将显示的机密复制到剪贴板",
     "tt_lite_decrypt_pass": "输入你的密码以移除钱包的加密",
     "tt_lite_encrypt": "用上方的密码加密钱包；加密后立即锁定，需要该密码才能解锁",