various improvements

stopped using private header folder (for ease of development - for now)
implemented basic gui service (WIP)
added sdkconfig.defaults to the repo
updated docs

components/nanobake/src/applications/services/gui/gui.h

@@ -6,6 +6,19 @@
 extern "C" {
 #endif
 
+#define RECORD_GUI "gui"
+
+typedef uint16_t screen_id_t;
+
+typedef struct Gui Gui;
+typedef void (*on_init_lvgl)(lv_obj_t*, screen_id_t);
+
+screen_id_t gui_screen_create(Gui* gui, on_init_lvgl callback);
+void gui_screen_free(Gui* gui, screen_id_t id);
+// TODO make internal
+void gui_screen_set_parent(Gui* gui, screen_id_t id, lv_obj_t* parent);
+lv_obj_t* gui_screen_get_parent(Gui* gui, screen_id_t id);
+
 extern const nb_app_t gui_app;
 
 #ifdef __cplusplus