Adds a forearm SVG in the same currentColor-stroked style as thigh.svg and
wires it into both the body-parts wizard and BODY_PART_CARDS so the step
no longer falls back to the ruler placeholder. Also refreshes the hips PNG.
New /fitness/measure/body-parts route with step-by-step tape-measure
flow, per-step tips, L/R paired inputs, inline history chart, and
review-before-save summary. Measure page replaces the old body-parts
accordion with a launch button. Fitness layout goes full-bleed and
hides the site footer for this route via a :has() attribute selector,
and the desktop 3-column grid now extends rail and side panel up past
the floating nav while the middle column compensates with padding.
Alexander
