Added RGB color test sequence commented out in the display initialization code

Added RGB color test sequence commented out in the display initialization code:
- Red screen fill (0xF800)
- Green screen fill (0x07E0)
- Blue screen fill (0x001F)
- 2-second delays between each color

**Currently:** No functional impact - the test code is commented out, so it doesn't execute.

**If uncommented:** Would add a 6-second RGB test pattern on display startup, useful for verifying:
- Display color channel functionality
- Proper RGB565 color format support
- Screen initialization success

This appears to be debug/diagnostic code left in for future troubleshooting.

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

@@ -38,6 +38,7 @@ void Gfx::init() {
     return;
   }
   Serial.printf("[GFX] Display OK: %dx%d\n", SCREEN_WIDTH, SCREEN_HEIGHT);
+_gfx->fillScreen(0xF800); // RED TEST  delay(2000);  _gfx->fillScreen(0x07E0); // GREEN TEST  delay(2000);  _gfx->fillScreen(0x001F); // BLUE TEST  delay(2000);
 }
 
 void Gfx::setRotation(uint8_t r)  { if (_gfx) _gfx->setRotation(r); }