feat(lite): wire send + new-address GUI to the lite controller (M3/M4)

Route the existing receive/balance/send UI to the lite controller in lite builds,
with no per-tab UI changes — the existing buttons just work:

- App::createNewZAddress / createNewTAddress: lite branch calls
  lite_wallet_->newAddress() (synchronous local key derivation), injects the new
  address into WalletState so the UI selects it next frame, and invokes the
  receive-tab callback. Placed before the full-node !connected guard.
- App::sendTransaction: lite branch builds a LiteSendRequest (DRGX -> zatoshis,
  memo; `from`/`fee` ignored since the backend selects inputs and adds the fee),
  fires the controller's async broadcast, and stashes the send_tab callback.
- App::update: drains takeBroadcastResult() and delivers txid/error to the stored
  callback, so the send_tab's existing "sending.../sent" flow works unchanged.

All branches guard on lite_wallet_ (null in full-node). Verified: lite app +
test suite + full-node variant all build/link clean; hygiene clean.

Backup/import UI (export seed/keys, import) is deferred — it needs new
secret-display UI rather than an existing button.

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

src/app.h

@@ -419,6 +419,9 @@ private:
 
     std::unique_ptr<config::Settings> settings_;
     std::unique_ptr<wallet::LiteWalletController> lite_wallet_;  // lite builds w/ linked backend
+    // Pending send_tab callback for an in-flight lite send (delivered in update() once the
+    // controller's async broadcast result arrives). Only one lite send runs at a time.
+    std::function<void(bool, const std::string&)> lite_send_callback_;
     std::unique_ptr<daemon::DaemonController> daemon_controller_;
     std::unique_ptr<daemon::XmrigManager> xmrig_manager_;
     util::AsyncTaskManager async_tasks_;