Fix 3.5C pins per CYD_PROJECT_GUIDE: BL=27, LD2420 TX=GPIO4, GT911 INT as INPUT.

Black-screen cause was TFT_BL=21; archive flashable firmware/cyd_35r.

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

include/touch.h

@@ -0,0 +1,6 @@
+#pragma once
+
+#include <lvgl.h>
+
+void touch_init();
+void touch_read_cb(lv_indev_t *indev, lv_indev_data_t *data);