I call it an ESD ring – surrounds the board edge to tie connector shells and such and catches the sparky-sparky events and dumps them back to battery/power-supply ground via a net-tie.
Kicad has no bezier curves, and arcs are super primitive, so it is challenging on an non-rectangular board to do it with traces. See my attempt to hack it:
But @blackcoffee’s technique looks like a good way to go.