Extract app frame and ui state services

src/legacy_app_frame_services.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include "app_core/app_frame.h"
+
+class App;
+class Node;
+
+#include <functional>
+
+namespace pp::panopainter {
+
+[[nodiscard]] bool update_legacy_app_ui_observer(App& app, Node* n);
+void watch_legacy_app_ui_children(
+    App& app,
+    const std::function<bool(Node*)>& observer,
+    bool skip_first_main_child);
+void update_legacy_canvas_toolbar(App& app);
+void execute_legacy_app_frame_update(
+    App& app,
+    const pp::app::AppFrameUpdatePlan& plan);
+void execute_legacy_app_frame_tick(App& app, float dt);
+void execute_legacy_app_frame_resize(App& app, float width, float height);
+
+} // namespace pp::panopainter