feat(wallet): detect a corrupt target wallet on switch + offer -salvagewallet repair

When a switch fails, the failure modal now distinguishes a CORRUPT target wallet
from other failures and offers a one-click repair:
- The switch worker watermarks the node's captured console output before the
  start and, if the node dies in init, scans this start's output for a corruption
  signature ("Failed to rename … .bak" / "salvage failed" / "wallet.dat corrupt" /
  "Error loading wallet") → sets switch_wallet_corrupt_.
- The Failed modal then shows an accurate "this wallet appears corrupt" message
  (instead of the generic "Couldn't open that wallet") plus a "Try to repair
  (salvage)" button that retries the switch with the target node started under
  -salvagewallet (recovers readable keypairs; implies -rescan).
- EmbeddedDaemon::setSalvageOnNextStart (one-shot, precedence salvage > zap >
  rescan) + controller forwarder; switchToWallet gains a salvage arg.

Salvage operates only on the corrupt target (never the good wallet, no fund
movement). Adversarially verified: output isolation, one-shot lifecycle, state
handling, re-entrancy, no success-path regression.

i18n (EN + 8 languages) + 2 new CJK glyphs baked into the subset font.

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

src/app.h

@@ -492,8 +492,8 @@ public:
     // (rescan only if it was never synced in this datadir). Per-wallet data follows automatically
     // via the identity-scoped caches (P1). No-op if that wallet is already active.
     // stopDaemonConfirmed: skip the "stop the running node?" confirmation (set true when re-entered from
-    // that dialog). The confirmation only appears when the node to restart was ADOPTED (externally running).
-    void switchToWallet(const std::string& walletFile, bool stopDaemonConfirmed = false);
+    // that dialog). salvage: start the target node with -salvagewallet (repair a corrupt wallet).
+    void switchToWallet(const std::string& walletFile, bool stopDaemonConfirmed = false, bool salvage = false);
     // Main-thread continuation: if a wallet switch's daemon failed to start, revert active_wallet_file.
     void processWalletSwitchRevert();
 
@@ -780,6 +780,10 @@ private:
     std::atomic<bool> wallet_switch_dialog_open_{false};
     std::string       wallet_switch_error_;
     double            wallet_switch_started_time_ = 0.0;  // ImGui::GetTime() captured on first progress frame (elapsed)
+    // Set when a failed switch's node output indicates the target wallet is CORRUPT — the Failed modal then
+    // offers a one-click "-salvagewallet" repair, retrying the switch to wallet_switch_target_file_.
+    std::atomic<bool> switch_wallet_corrupt_{false};
+    std::string       wallet_switch_target_file_;  // the wallet we were switching TO (for a salvage retry)
 
     // 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.