Hold the knob to open a six-row menu: save/remove the playing camera as
a favourite (12 NVS slots), play or forget favourites, choose the
source (random insecam or favourites), time per camera, listing,
screen and ring brightness, caption, and reboot into Wi-Fi setup.
Settings live in NVS and override the Kconfig first-boot defaults.
Camera URLs are stored with their COUNTER placeholder so favourites get
a fresh cache-buster on every visit.
