fix(security): only a real wrong passphrase counts toward unlock lockout

A failed wallet unlock was always treated as a wrong guess: the lockout
counter was bumped and the back-off curve armed no matter why the RPC
failed. A busy or warming-up node, a transport timeout, or a wallet that
is not actually encrypted would all eat an attempt and could push a user
into a lockout without a single mistyped passphrase.

The failed call is now classified before it is acted on:

- Only the daemon's "passphrase incorrect" error counts as a wrong
  guess and advances the lockout.
- A warming-up or unreachable node, a reply timeout, or a full queue is
  reported as a transient busy-node condition with no attempt charged.
- A "wallet is not encrypted" reply refreshes the local encryption state
  instead of penalising the user.
- Any unknown error surfaces its message without touching the counter.

The PIN path got the same treatment: when the vault decrypts correctly
but the unlock RPC then fails for a non-credential reason, the attempt
is no longer counted.

Tests cover the classification of each failure kind.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

res/lang/de.json

@@ -1707,6 +1707,7 @@
     "sec_total_elapsed_fmt": "Gesamtdauer: %dm %02ds",
     "sec_unlock_button": "Entsperren",
     "sec_unlock_failed_prefix": "Entsperren fehlgeschlagen: ",
+    "sec_unlock_node_busy": "The node is busy; try again in a moment.",
     "sec_unlocking_fmt": "Entsperren%s",
     "sec_use_passphrase_instead": "Stattdessen Passphrase verwenden",
     "sec_use_pin_instead": "Stattdessen PIN verwenden",

res/lang/es.json

@@ -1707,6 +1707,7 @@
     "sec_total_elapsed_fmt": "Tiempo total: %dm %02ds",
     "sec_unlock_button": "Desbloquear",
     "sec_unlock_failed_prefix": "Error al desbloquear: ",
+    "sec_unlock_node_busy": "The node is busy; try again in a moment.",
     "sec_unlocking_fmt": "Desbloqueando%s",
     "sec_use_passphrase_instead": "Usar frase de contraseña en su lugar",
     "sec_use_pin_instead": "Usar PIN en su lugar",

res/lang/fr.json

@@ -1707,6 +1707,7 @@
     "sec_total_elapsed_fmt": "Temps total écoulé : %dm %02ds",
     "sec_unlock_button": "Déverrouiller",
     "sec_unlock_failed_prefix": "Échec du déverrouillage : ",
+    "sec_unlock_node_busy": "The node is busy; try again in a moment.",
     "sec_unlocking_fmt": "Déverrouillage%s",
     "sec_use_passphrase_instead": "Utiliser une phrase secrète",
     "sec_use_pin_instead": "Utiliser un PIN",

res/lang/ja.json

@@ -1707,6 +1707,7 @@
     "sec_total_elapsed_fmt": "合計経過時間: %d分 %02d秒",
     "sec_unlock_button": "ロック解除",
     "sec_unlock_failed_prefix": "ロック解除に失敗しました: ",
+    "sec_unlock_node_busy": "The node is busy; try again in a moment.",
     "sec_unlocking_fmt": "ロック解除中%s",
     "sec_use_passphrase_instead": "代わりにパスフレーズを使用",
     "sec_use_pin_instead": "代わりにPINを使用",

res/lang/ko.json

@@ -1707,6 +1707,7 @@
     "sec_total_elapsed_fmt": "총 경과 시간: %d분 %02d초",
     "sec_unlock_button": "잠금 해제",
     "sec_unlock_failed_prefix": "잠금 해제 실패: ",
+    "sec_unlock_node_busy": "The node is busy; try again in a moment.",
     "sec_unlocking_fmt": "잠금 해제 중%s",
     "sec_use_passphrase_instead": "대신 암호문 사용",
     "sec_use_pin_instead": "대신 PIN 사용",

res/lang/pt.json

@@ -1707,6 +1707,7 @@
     "sec_total_elapsed_fmt": "Tempo total: %dm %02ds",
     "sec_unlock_button": "Desbloquear",
     "sec_unlock_failed_prefix": "Falha ao desbloquear: ",
+    "sec_unlock_node_busy": "The node is busy; try again in a moment.",
     "sec_unlocking_fmt": "Desbloqueando%s",
     "sec_use_passphrase_instead": "Usar frase-senha",
     "sec_use_pin_instead": "Usar PIN",

res/lang/ru.json

@@ -1707,6 +1707,7 @@
     "sec_total_elapsed_fmt": "Всего прошло: %dм %02dс",
     "sec_unlock_button": "Разблокировать",
     "sec_unlock_failed_prefix": "Ошибка разблокировки: ",
+    "sec_unlock_node_busy": "The node is busy; try again in a moment.",
     "sec_unlocking_fmt": "Разблокировка%s",
     "sec_use_passphrase_instead": "Использовать парольную фразу",
     "sec_use_pin_instead": "Использовать PIN",

res/lang/zh.json

@@ -1707,6 +1707,7 @@
     "sec_total_elapsed_fmt": "总耗时：%d 分 %02d 秒",
     "sec_unlock_button": "解锁",
     "sec_unlock_failed_prefix": "解锁失败：",
+    "sec_unlock_node_busy": "The node is busy; try again in a moment.",
     "sec_unlocking_fmt": "正在解锁%s",
     "sec_use_passphrase_instead": "改用密码短语",
     "sec_use_pin_instead": "改用 PIN",