Give the wounded frames legs that actually move

The pair alternated but the feet stayed put: the generator had swapped the arms
and torso and redrawn the same legs. Measured it rather than squinting — the
lower third of the two wounded frames differed by 3.7% and 4.6%, where a healthy
walk pair differs by 60-70%. That is a body sliding, which is exactly what Oliver
saw.

Regenerated with the stride as the entire brief (33% for the shambler), and where
the generator would not move them, mirrored the leg band in place instead: a
side-on walk swaps its stride under a horizontal flip of the legs alone, same
pixels, same palette, no dice roll. The coated shambler and the steward are that
(28% and 31%).

Audited every wound pair the same way while I was in there — the racket zombie's
two stages and the brute were already fine.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

render.js

@@ -155,7 +155,7 @@ export function proj(x, y, z) {
 
 // ---------------------------------------------------------------- sprites ----
 // assets/<name>.png; game falls back to code-drawn figures until sprites load.
-const SPRV = 58; // asset cache-buster — bump with main.js?v=N (see the img.src note below)
+const SPRV = 59; // asset cache-buster — bump with main.js?v=N (see the img.src note below)
 const SPR = {};
 for (const n of ['p_idle1','p_idle2','p_bounce','p_bounce2','p_toss','p_smash','p_run1','p_run2','p_run3','p_run4','p_swing1','p_swing2','p_die1','p_die2',
                  'o_idle1','o_idle2','o_bounce','o_bounce2','o_toss','o_smash','o_run1','o_run2','o_swing1','o_swing2',