fix upload .pano suffix, make first layer fixed when animating

engine/app_layout.cpp

@@ -601,6 +601,12 @@ void App::initLayout()
                     layers->handle_layer_opacity(l, .25f);
                 }
 
+                // First layer always visible
+                {
+                    auto l = layers->get_layer_at(0);
+                    layers->handle_layer_opacity(l, 1.0f);
+                }
+
                 if (frame_text)
                 {
                     char str[16];