chatgui: fix all animations showing the same TGS (rlottie model cache key collision)

lottie_animation_from_data uses 'key' as a cache key for parsed models.
All LottieIcon instances were created with key="", causing rlottie's
model cache to return the first loaded animation for all subsequent
requests. Only visible on Windows where rlottie cache is enabled by
default.

Fix: pass unique animPath as key to each LottieIcon constructor.
Also replaced fprintf(stderr) diag with GUI_INFO logging via
AnimTimer::logRegisteredIcons() in debug_ui.h.

tools/chatgui/src/mainwindow.cpp

@@ -143,6 +143,8 @@ void MainWindow::setupNode() {
 
     if (!m_node->start(m_cfgPath))
         qWarning("Failed to start UtunNode");
+    else
+        AnimTimer::instance()->logRegisteredIcons();
 }
 
 void MainWindow::setupMessaging() {