PortBtn was defined inside AntGeniusPanel, so every render produced a new
component type and React unmounted/remounted every port button. Normally
re-renders are rare so it's invisible, but the CW decoder floods the app with
cw:text/cw:status events (re-render many times a second), tearing the buttons
down between mousedown and mouseup — the click never completed and the antenna
never switched. Move PortBtn to module scope (stable identity) and pass
onActivate/t as props.