feat(wallet): live progress modal for wallet switching

The "Stop the running node?" confirm modal now stays open through the entire
switch — stop → wait-for-exit → start → reconnect — showing a live phase, and
auto-closes the moment the new node connects. This turns the up-to-a-minute
graceful-shutdown wait from an apparent freeze into visible progress.

- WalletSwitchPhase (Stopping/Starting/Reconnecting/Failed) + atomic phase and
  dialog-open flags; the worker advances the phase, onConnected closes the modal,
  and a failed switch shows the accurate reason with a Close button.
- Owned switches (no confirm) also show the progress modal directly.
- "Continue in background" escape hatch so a long rescan / a hung startup never
  traps the user (the switch keeps running; a toast reports the result).
- isWalletSwitchInProgress() keeps the frame loop redrawing so the phase text and
  spinner animate while otherwise idle.
- i18n (EN + 8 languages, additive) + a modal-switch-progress sweep surface.

State machine adversarially verified 6/6 (thread-safety, no stuck modal,
confirm→progress transition, owned/unowned, no phase leak, redraw scoping).

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

res/lang/ja.json

@@ -1294,6 +1294,13 @@
     "sweep_to": "集約先:",
     "sweep_toggle": "ウォレットに集約（鍵は保持しない）",
     "sweep_tx": "取引:",
+    "switch_progress_background": "バックグラウンドで続行",
+    "switch_progress_failed_title": "ウォレットの切り替えに失敗しました",
+    "switch_progress_hint": "正常なシャットダウンには最大1分かかることがあります。",
+    "switch_progress_reconnecting": "再接続しています",
+    "switch_progress_starting": "新しいウォレットでノードを起動しています",
+    "switch_progress_stopping": "現在のノードを停止しています",
+    "switch_progress_title": "ウォレットを切り替え中",
     "switch_stopnode_body": "ウォレットを切り替えると、選択したウォレットでノードが再起動します。実行中のノードは停止され、新しいウォレットで再起動されます。意図的に起動したままにしていた場合は、自動的に復帰します。",
     "switch_stopnode_confirm": "ノードを停止して切り替え",
     "switch_stopnode_title": "実行中のノードを停止しますか？",