Match LiquidCrystal_I2C init delays; add Map button for alternate PCF8574 wiring; warn about blue contrast pot. Co-authored-by: Cursor <cursoragent@cursor.com>
PCF8574 backpack on SDA=GPIO22/SCL=GPIO27, demo/hello/clear/backlight UI, and flashable firmware/cyd package. Co-authored-by: Cursor <cursoragent@cursor.com>