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.cpp

@@ -3919,6 +3919,15 @@ void App::renderSwitchStopDaemonDialog()
         // rather than repeating the title.
         ui::material::DialogWarningHeader(wallet_switch_error_.c_str());
         ImGui::Dummy(ImVec2(0, ui::Layout::spacingMd()));
+        // If the node reported the target wallet as corrupt, offer a one-click -salvagewallet repair
+        // (retries the switch to that wallet with recovery enabled).
+        if (switch_wallet_corrupt_.load()) {
+            if (ui::material::TactileButton(TR("switch_corrupt_repair"), ImVec2(240.0f * dp, 0))) {
+                const std::string target = wallet_switch_target_file_;
+                switchToWallet(target, /*stopDaemonConfirmed=*/true, /*salvage=*/true);  // reopens the progress modal
+            }
+            ImGui::SameLine();
+        }
         if (ui::material::TactileButton(TR("close"), ImVec2(110.0f * dp, 0))) {
             wallet_switch_dialog_open_.store(false);
             wallet_switch_phase_.store(static_cast<int>(WalletSwitchPhase::None));