Button E was PIN_BUTTON1 with a hand-rolled FunctionButton map in
InputBroker (single press: ping, double: privacy toggle, 5 s hold:
shutdown). The rotary encoder already drives the UI, so define the pin as
CANCEL_BUTTON_PIN instead and drop the M8 special case: a press now
cancels and a 4 s hold shuts down, through the generic cancel button.
variant_shutdown() follows the rename so the wake-on-press pin is still
parked and sensed.
Claude-Session: https://claude.ai/code/session_01B7bFRZ9bBMRr7KPBF8rmzu
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
