Function kitty_placement_spec 

pub fn kitty_placement_spec(fit: LogoFit) -> String

Builds the Kitty graphics-protocol placement keys (c= / r=) for a fitted logo.

Deliberately emits only the limiting dimension. Kitty derives the other from the image’s real aspect ratio, whereas specifying both makes it scale each axis independently to fill the rectangle exactly — and because cells are indivisible, the rounded rectangle is never quite the image’s aspect, so passing both leaves a residual stretch even when the numbers are computed correctly (measured at 9% for the Fedora logo). Passing one leaves none.

The reservation plan_layout makes is div_ceil-rounded and therefore always covers what Kitty then draws.