fix(lite): welcome "Restore from seed" now prompts for the seed inline

On first run the lite welcome screen's "Restore from seed" button only showed a
hint toast and bounced the user to Settings, dismissing the welcome with no
wallet open — it never prompted for a seed. Add a real restore step to the
welcome wizard: a seed-phrase field + optional birthday height, which calls
beginRestoreWalletAsync() (same server failover as create/open), shows
"Restoring…" progress, then completes (wallet syncs) or surfaces the error to
retry. The seed buffer is wiped on success/Back and in finish().

(The Settings -> Lite -> Restore path already prompted for a seed; this fixes
the first-run welcome path.)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app.cpp

@@ -2022,6 +2022,11 @@ void App::renderLiteFirstRunPrompt()
     static int progress = 0;             // # words confirmed in order
     static double wrongFlashUntil = 0.0; // brief "not the next word" hint
     static bool creating = false;        // async create (with failover) in flight
+    // Restore-from-seed step (step 3). The seed buffer is SECRET — wiped in finish() and on Back.
+    static char restoreSeed[512] = {};
+    static int  restoreBirthday = 0;
+    static bool restoring = false;       // async restore in flight
+    static std::string restoreErr;
 
     // The welcome page is only relevant before any wallet exists; once create has started
     // (creating) or reached reveal/verify (step>0), keep showing it through to completion even
@@ -2035,6 +2040,10 @@ void App::renderLiteFirstRunPrompt()
 
     auto finish = [&]() {
         wallet::secureWipeLiteSecret(seed);
+        sodium_memzero(restoreSeed, sizeof(restoreSeed));
+        restoreBirthday = 0;
+        restoring = false;
+        restoreErr.clear();
         words.clear();
         chips.clear();
         progress = 0;
@@ -2105,9 +2114,7 @@ void App::renderLiteFirstRunPrompt()
                 }
                 ImGui::SameLine();
                 if (ImGui::Button(TR("lite_welcome_restore"), ImVec2(btnW, 0))) {
-                    ui::Notifications::instance().info(TR("lite_welcome_restore_hint"), 8.0f);
+                    step = 3;  // inline seed-entry restore (see step 3 below)
-                    setCurrentPage(ui::NavPage::Settings);
-                    finish();
                 }
                 ImGui::Spacing();
                 if (ImGui::Button(TR("lite_welcome_later"),
@@ -2160,7 +2167,7 @@ void App::renderLiteFirstRunPrompt()
                 ui::Notifications::instance().success(TR("lite_welcome_created"), 6.0f);
                 finish();
             }
-        } else {  // step == 2
+        } else if (step == 2) {
             // ── Verify: tap the words in order ──────────────────────────────────────
             ImGui::PushFont(ui::material::Type().subtitle1());
             ImGui::TextUnformatted("Confirm your backup");
@@ -2213,6 +2220,76 @@ void App::renderLiteFirstRunPrompt()
                 ui::Notifications::instance().success(TR("lite_welcome_created"), 6.0f);
                 finish();
             }
+        } else if (step == 3) {
+            // ── Restore from an existing seed phrase ────────────────────────────────
+            ImGui::PushFont(ui::material::Type().subtitle1());
+            ImGui::TextUnformatted(TR("lite_restore_title"));
+            ImGui::PopFont();
+            ImGui::Spacing();
+            ImGui::PushTextWrapPos(ImGui::GetCursorPosX() + 380.0f);
+            ImGui::TextUnformatted(TR("lite_restore_intro"));
+            ImGui::PopTextWrapPos();
+            ImGui::Spacing();
+
+            if (restoring) {
+                // Async restore (with server failover) in flight — driven by pumpAsyncOpen().
+                ImGui::TextUnformatted("Restoring your wallet\xE2\x80\xA6");
+                if (lite_wallet_->walletOpen()) {
+                    ui::Notifications::instance().success(TR("lite_restore_ok"), 6.0f);
+                    finish();  // wipes restoreSeed; the wallet then syncs from the lite server
+                } else if (!lite_wallet_->openInProgress() &&
+                           !lite_wallet_->lastOpenError().empty()) {
+                    restoreErr = lite_wallet_->lastOpenError();
+                    restoring = false;  // back to the form so the user can fix and retry
+                }
+            } else {
+                ImGui::TextUnformatted(TR("lite_restore_seed_label"));
+                ImGui::InputTextMultiline("##LiteRestoreSeed", restoreSeed, sizeof(restoreSeed),
+                                          ImVec2(380.0f, ImGui::GetTextLineHeight() * 3.2f));
+                ImGui::Spacing();
+                ImGui::TextUnformatted(TR("lite_restore_birthday_label"));
+                ImGui::SetNextItemWidth(160.0f);
+                ImGui::InputInt("##LiteRestoreBirthday", &restoreBirthday);
+                if (restoreBirthday < 0) restoreBirthday = 0;
+
+                if (!restoreErr.empty()) {
+                    ImGui::Spacing();
+                    ImGui::PushStyleColor(ImGuiCol_Text, ui::material::Error());
+                    ImGui::PushTextWrapPos(ImGui::GetCursorPosX() + 380.0f);
+                    ImGui::TextUnformatted(restoreErr.c_str());
+                    ImGui::PopTextWrapPos();
+                    ImGui::PopStyleColor();
+                }
+                ImGui::Spacing(); ImGui::Spacing();
+
+                // Trim surrounding whitespace from the entered seed.
+                std::string seedTrim(restoreSeed);
+                while (!seedTrim.empty() && std::isspace((unsigned char)seedTrim.front())) seedTrim.erase(seedTrim.begin());
+                while (!seedTrim.empty() && std::isspace((unsigned char)seedTrim.back())) seedTrim.pop_back();
+
+                ImGui::BeginDisabled(seedTrim.empty());
+                if (ImGui::Button(TR("lite_restore_btn"), ImVec2(btnW, 0))) {
+                    wallet::LiteWalletRestoreRequest req;
+                    req.seedPhrase = seedTrim;
+                    req.birthday   = static_cast<unsigned long long>(std::max(0, restoreBirthday));
+                    req.overwrite  = lite_wallet_->walletExists();  // replace any existing wallet file
+                    if (lite_wallet_->beginRestoreWalletAsync(std::move(req))) {
+                        restoreErr.clear();
+                        restoring = true;
+                    } else {
+                        restoreErr = lite_wallet_->lastOpenError().empty()
+                                         ? std::string("Could not start restore")
+                                         : lite_wallet_->lastOpenError();
+                    }
+                }
+                ImGui::EndDisabled();
+                ImGui::SameLine();
+                if (ImGui::Button("Back", ImVec2(80, 0))) {
+                    sodium_memzero(restoreSeed, sizeof(restoreSeed));
+                    restoreErr.clear();
+                    step = 0;
+                }
+            }
         }
         ImGui::EndPopup();
     }

src/util/i18n.cpp

@@ -655,6 +655,12 @@ void I18n::loadBuiltinEnglish()
         strings_["lite_welcome_created"] = "Wallet created — back up your recovery phrase now in Settings → Backup & keys";
         strings_["lite_welcome_restore_hint"] = "Restore your wallet under Settings → Lite wallet request";
         strings_["lite_welcome_create_failed"] = "Could not create wallet";
+        strings_["lite_restore_title"] = "Restore from seed phrase";
+        strings_["lite_restore_intro"] = "Enter your recovery seed phrase. The wallet will be restored and then synced from the lite server.";
+        strings_["lite_restore_seed_label"] = "Seed phrase (words separated by spaces)";
+        strings_["lite_restore_birthday_label"] = "Birthday block (optional — 0 scans from the start, slower)";
+        strings_["lite_restore_btn"] = "Restore wallet";
+        strings_["lite_restore_ok"] = "Wallet restored — syncing from the lite server…";
         // Lite send-time unlock prompt.
         strings_["lite_unlock_title"] = "Unlock wallet";
         strings_["lite_unlock_msg"] = "Enter your passphrase to unlock the wallet for spending.";