fix: add missing #include <Arduino.h> to GFX/GT911 drivers

Required for uint16_t, Serial, millis() etc. when compiling
outside the .ino (Arduino IDE auto-includes Arduino.h for .ino
files but not for standalone .cpp files).

sketches/doorbell-touch-esp32-32e/DisplayDriverGFX.cpp

@@ -4,6 +4,7 @@
 // For the TFT_eSPI path this file compiles to nothing.
 // ═══════════════════════════════════════════════════════════════════
 #include "BoardConfig.h"
+#include <Arduino.h>
 
 #if USE_ARDUINO_GFX
 

sketches/doorbell-touch-esp32-32e/TouchDriverGT911.cpp

@@ -1,4 +1,5 @@
 #include "BoardConfig.h"
+#include <Arduino.h>
 
 #if USE_TOUCH_GT911