Phase 3: procedural gore piles

Kills now grow 3D-ish gore mounds, not just flat stains. zombies.js gains
a piles array {x,z,size,seed}: a kill within 0.6m of a pile grows it
(size +1, cap 4), else starts a new one (cap 30, oldest shifts out).
Ball boys shave overlapping piles at size -= dt*0.25 — far slower than
stain mopping (dt*1.6) — so net growth wins over a long match. Splatter
particles bumped 14→24, ~1/3 dark and longer-lived (settling gore),
render reads pt.dark for colour.

render.js draws each pile as seeded pixel-art blobs (mulberry32 from
p.seed): N=6+size*5 blobs, offset within size*0.28m, lifted up to
size*0.14m so the pile has visible height, weighted gore colours + ~10%
bone flecks. Blobs are built once and rebuilt only when the pile GROWS
(builtSize guard) — never on the per-frame mop-shrink — and each pile
costs a single proj() call (blob screen positions offset from the base).
Piles draw split far/near of the net like zombies so height occludes
right. window.T exposes render/piles/gore/parts for verification.

Verified via window.T: clustered kills build tall dense mounds while
singles stay small (screenshot), avg render 0.61ms with 10 piles, 0 blob
rebuilds across 120 frames, mop shrinks a size-4 pile at exactly 0.25/s,
no console errors.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

main.js

@@ -8,7 +8,7 @@ import { P, O, ball, score, G, setupPoint } from './state.js';
 import { update, keyPressed, solveShot, inServeBox, inCourt, forceZombies } from './gameplay.js';
 import { fitViewport, render, proj } from './render.js';
 import { voice } from './audio.js';
-import { zombies, spawnZombie } from './zombies.js';
+import { zombies, spawnZombie, piles, gore, parts } from './zombies.js';
 import { cv } from './dom.js';
 import './input.js';
 
@@ -54,6 +54,6 @@ cv.addEventListener('pointerdown', e => {
 requestAnimationFrame(frame);
 
 // exposed for in-browser sanity checks and simulated playtests
-window.T = { TUNE, ball, P, O, score, G, zombies, spawnZombie, solveShot, inServeBox, inCourt, proj, setupPoint,
-  step: dt => update(dt), press: keyPressed,
+window.T = { TUNE, ball, P, O, score, G, zombies, spawnZombie, piles, gore, parts, solveShot, inServeBox, inCourt, proj, setupPoint,
+  step: dt => update(dt), render, press: keyPressed,
   get phase() { return G.phase; }, set phase(v) { G.phase = v; } };