Raspberry Pi Pico Chasing LED (6 LEDs, GP14 → GP9)

Classic "chasing LED" animation with Pico — 6 LED version! 6 LEDs light up left-to-right sequentially — like light walking down the row. Learn Python list, list comprehension ([Pin(p, Pin.OUT) for p in LED_PINS]), for loop with pin control and enumerate(). 6 LEDs on GP9-GP14, each with 220Ω current-limiting resistor. Very clean code: instead of defining 6 LEDs one by one, we use a list — you can add LEDs up to the number of free, usable GPIO pins, each with its own resistor. Controlling 100 inde