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/zh.json

@@ -1294,6 +1294,13 @@
     "sweep_to": "归集到：",
     "sweep_toggle": "归集到我的钱包（不保留密钥）",
     "sweep_tx": "交易：",
+    "switch_progress_background": "在后台继续",
+    "switch_progress_failed_title": "切换钱包失败",
+    "switch_progress_hint": "正常关闭最多可能需要一分钟。",
+    "switch_progress_reconnecting": "正在重新连接",
+    "switch_progress_starting": "正在以新钱包启动节点",
+    "switch_progress_stopping": "正在停止当前节点",
+    "switch_progress_title": "正在切换钱包",
     "switch_stopnode_body": "切换钱包会以所选钱包重启节点。正在运行的节点将被停止并以新钱包重新启动——如果你是特意让它保持运行的，它会自动重新启动。",
     "switch_stopnode_confirm": "停止节点并切换",
     "switch_stopnode_title": "停止正在运行的节点？",