fix(chat): un-hide on lite receives + scope the contact picker per wallet

Review of fc414ee found two issues:

- HIGH: the lite variant harvests chat via ingestLiteChatMemos, which called
  ingest() without the newIncomingCids out-param — so the un-hide never ran and a
  hidden conversation stayed hidden PERMANENTLY on new messages (chat is default-ON
  and fully supported in Lite), breaking the "a new message brings it back"
  invariant. Wire the same un-hide + off-tab toast into the lite path.

- LOW: the new-conversation contact picker listed every z-address contact,
  ignoring the per-wallet scope the Contacts tab enforces — leaking another
  wallet's scoped contact into this wallet's picker. Apply the same scope test
  (global + legacy fail open; "w:" scopes match the active wallet).

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

src/app_network.cpp

@@ -3147,7 +3147,22 @@ void App::ingestLiteChatMemos(const wallet::LiteWalletAppRefreshModel& model)
         auto extracted = chat::extractHushChatTransactionMetadata(entry.second, true);
         for (auto& meta : extracted.metadata) metadata.push_back(std::move(meta));
     }
-    if (!metadata.empty()) chat_service_.ingest(metadata, txTimestamps, std::time(nullptr));
+    if (!metadata.empty()) {
+        std::vector<std::string> newChatCids;
+        chat_service_.ingest(metadata, txTimestamps, std::time(nullptr), &newChatCids);
+        // Mirror the full-node paths: a new incoming message un-hides a hidden conversation (you can't
+        // un-receive), and a non-muted new message toasts when we're off the Chat tab.
+        if (settings_) {
+            bool unhid = false;
+            for (const auto& cid : newChatCids)
+                if (settings_->isChatHidden(cid)) { settings_->setChatHidden(cid, false); unhid = true; }
+            if (unhid) settings_->save();
+        }
+        if (current_page_ != ui::NavPage::Chat &&
+            std::any_of(newChatCids.begin(), newChatCids.end(),
+                        [this](const std::string& cid){ return !(settings_ && settings_->isChatMuted(cid)); }))
+            ui::Notifications::instance().info(TR("chat_new_message_toast"));
+    }
 }
 
 bool App::lockLiteWallet()

src/ui/windows/chat_tab.cpp

@@ -635,9 +635,15 @@ void RenderChatTab(App* app)
             // Selecting one fills the field above (manual paste still works).
             ImGui::SetNextItemWidth(fieldW);
             if (ImGui::BeginCombo("##newzpick", TR("chat_pick_contact"), ImGuiComboFlags_HeightLarge)) {
+                const std::string activeHash = app->activeWalletScopeId();  // per-wallet contact scope
                 int shown = 0;
                 for (const auto& e : book.entries()) {
                     if (e.address.empty() || e.address[0] != 'z') continue;   // chat requires a z-address
+                    // Respect the same per-wallet scope the Contacts tab enforces — don't leak another
+                    // wallet's scoped contact into this wallet's picker (global + legacy fail open).
+                    const bool visible = e.isGlobal() ||
+                        (e.scope.rfind("w:", 0) == 0 ? (!activeHash.empty() && e.scope == activeHash) : true);
+                    if (!visible) continue;
                     ++shown;
                     const std::string item = e.label + "   " + shorten(e.address, 16, 8);
                     if (ImGui::Selectable(item.c_str())) {