The walk polygon was rendered 25% too large due to an erroneous * 1.25
factor on scale_x / scale_y. On top of this, GAIT_SHIFT_X=-6.383 and
GAIT_SHIFT_Y=3.76 (internal cat.js group transforms) were incorrectly
ported as canvas offsets, pushing the polygon partially above the top
edge of the overlay window (visible clipping).
Root cause: the SVG viewBox is 0 0 150 120. Walk polygon coordinates
span 4-145 in X and 8-112 in Y -- already fitting the viewBox with no
additional scaling or translation needed.
Fix: use scale_x = (cat_width / 150) * SS and scale_y = (cat_height / 120) * SS
with zero offset. Walk frame now renders at the same visual size as paw/
scruff/tail/stretch frames (all on a cat_width x cat_height canvas).
Result: cat body is no longer clipped at the top and matches size of all
other animation states.