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>

src/app_sweep.cpp

@@ -379,6 +379,11 @@ void App::buildSweepCatalog()
     add("modal-switch-stopnode", ui::NavPage::Settings,
         [](App& a) { a.pending_switch_wallet_file_ = "wallet-savings.dat"; a.show_switch_stop_daemon_confirm_ = true; },
         [](App& a) { a.show_switch_stop_daemon_confirm_ = false; a.pending_switch_wallet_file_.clear(); });
+    add("modal-switch-progress", ui::NavPage::Settings,
+        [](App& a) { a.wallet_switch_phase_.store(static_cast<int>(App::WalletSwitchPhase::Stopping));
+                     a.wallet_switch_dialog_open_.store(true); },
+        [](App& a) { a.wallet_switch_dialog_open_.store(false);
+                     a.wallet_switch_phase_.store(static_cast<int>(App::WalletSwitchPhase::None)); });
     // Wave-2 fund/secret dialogs (setup never fires the async RPC — no button is clicked).
     add("modal-shield", ui::NavPage::Send,
         [](App&) { ui::ShieldDialog::showShieldCoinbase(); },