stax: add UI implementation

src_nbgl/ui_nbgl.h

@@ -0,0 +1,19 @@
+#ifndef _UI_NBGL_H_
+#define _UI_NBGL_H_
+
+#include <nbgl_use_case.h>
+#include <nbgl_page.h>
+#include <shared_context.h>
+
+#define SHARED_BUFFER_SIZE SHARED_CTX_FIELD_1_SIZE
+extern uint8_t staxSharedBuffer[SHARED_BUFFER_SIZE];
+
+extern nbgl_page_t* pageContext;
+
+void releaseContext(void);
+
+void ui_idle(void);
+void ui_menu_settings(void);
+void ui_menu_about(void);
+
+#endif  // _UI_NBGL_H_