Calibrate touch from serial logs: invert physical X axis.

Bottom LVGL buttons were mapped to the top; add on-screen logic coordinate debug.

Co-authored-by: Cursor <cursoragent@cursor.com>

include/ui.h

@@ -5,3 +5,4 @@
 void ui_create();
 void ui_update(const SdCardInfo &info);
 void ui_refresh_audio_buttons();
+void ui_set_touch_debug(int16_t lx, int16_t ly, bool down);