Route render debug callback through platform services

src/app.h

@@ -199,6 +199,7 @@ public:
     void bind_default_render_target();
     void bind_main_render_target();
     void apply_render_platform_hints();
+    void install_render_debug_callback();
     void begin_render_capture_frame();
     void end_render_capture_frame();
     [[nodiscard]] bool platform_deletes_recorded_files_on_clear();