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.h

@@ -139,6 +139,9 @@ public:
      * @brief Whether we are in the shutdown phase
      */
     bool isShuttingDown() const { return shutting_down_; }
+    // True while the wallet-switch progress modal is open — keeps the frame loop redrawing so its live
+    // phase/spinner update in real time even when the app is otherwise idle.
+    bool isWalletSwitchInProgress() const { return wallet_switch_dialog_open_.load(); }
     wallet::WalletCapabilities walletCapabilities() const { return wallet::currentWalletCapabilities(); }
     bool isLiteBuild() const { return wallet::isLiteBuild(walletCapabilities()); }
     bool supportsEmbeddedDaemon() const { return wallet::supportsEmbeddedDaemon(walletCapabilities()); }
@@ -768,6 +771,14 @@ private:
     // sets these and defers to renderSwitchStopDaemonDialog; confirming re-calls switchToWallet(w, true).
     bool show_switch_stop_daemon_confirm_ = false;
     std::string pending_switch_wallet_file_;
+    // Live progress for the switch modal: it stays open from confirm through stop → wait-for-exit → start →
+    // reconnect and auto-closes when the new node connects (onConnected). Phase is worker-updated;
+    // dialog_open_ gates rendering — both atomic since onConnected/the worker may run off the main thread.
+    // error_ is written only on the main thread (processWalletSwitchRevert) and read by the (main-thread) UI.
+    enum class WalletSwitchPhase : int { None = 0, Stopping, Starting, Reconnecting, Failed };
+    std::atomic<int>  wallet_switch_phase_{0};
+    std::atomic<bool> wallet_switch_dialog_open_{false};
+    std::string       wallet_switch_error_;
 
     // Set by the deleteBlockchainData worker (item count); the main loop surfaces a completion toast
     // and resets it to -1. Atomic because the worker thread writes it and the UI thread reads/clears it.