Runner is glass; battery pass (30fps cap, cached piles, GC fixes)

Runner counter (no new weapon needed — one you don't hold when it shrieks
can't save you): the sprinter is now a GLASS CANNON — any ball contact at
any quality bursts it (main ball and triple-serve side balls; melee and
pellets already killed it). The hold-to-aim auto-lock targets the most
advanced zombie = the charging runner, so touch-and-release is the panic
button. Plus runnerVMax 4.2: the late-game speed ramp is capped so runners
stay humanly reactable.

Battery (iPhone drain):
- TUNE.fps = 30 (T-panel tunable, 0/60 = uncapped): frame-skip cap in the
  RAF loop — halves paint work on a 810x1440 canvas, the dominant cost.
  dt clamp raised 0.033 -> 0.04 so 30fps doesn't run 1% slow-motion.
- Gore piles pre-rendered to per-pile cached canvases (rebuilt on growth /
  orientation change): 1 drawImage per pile per frame instead of ~26
  ellipse paths — late-game courts had ~800 path fills per frame.
- matchMedia('(pointer: coarse)') hoisted out of the render loop (was
  allocating a MediaQueryList every pretoss frame).

Verified: weak (pow .05) ball kills a runner; max-ramp runner v = 4.2
exactly; piles render from cache (screenshot, pl.cv set); frame-cap
arithmetic yields clean every-other-tick at 60Hz RAF (RAF itself is paused
in this pane — logic deterministic); tennis serve benchmark 30/36 across
runs (flub-band; diff is provably tennis-neutral); no console errors.

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

zombies.js

@@ -20,7 +20,7 @@ let spawnT = 1.5, moanT = 3;
 export function spawnZombie(x, z, variant) {
   const ramp = 1 + Math.min(1.5, G.splatT / 70); // they get faster the longer you survive
   const zb = { x, z, v: TUNE.zSpeed * ramp * (0.8 + Math.random() * 0.4), walkT: Math.random() * 9, variant };
-  if (variant === 'f') { zb.v *= TUNE.runnerSpeed; shriek(); } // the shriek is the fairness contract
+  if (variant === 'f') { zb.v = Math.min(TUNE.runnerVMax, zb.v * TUNE.runnerSpeed); shriek(); } // shriek = the fairness contract; capped so late runners stay reactable
   if (variant === 'g') { zb.v *= 0.55; zb.hp = TUNE.bruteHp; } // slow, but soaks hits
   if (variant === 's') zb.shieldT = 0;                         // chair up; > 0 = seconds of stagger left
   zombies.push(zb);
@@ -243,6 +243,7 @@ export function updateZombies(dt) {
           ball.vx *= 0.4; ball.vz *= -0.2; ball.lastHit = 'X'; // ball caroms off the chair, spent
           continue;
         }
+        if (zb.variant === 'f') { splatter(i); continue; } // the sprinter is GLASS — any touch, any quality, it bursts
         // chair-down shield zombies (and anything hit from behind) obey the normal rules:
         if ((ball.pow || 0) >= TUNE.zSplatQ) { splatter(i); continue; }
         zb.z -= TUNE.zPushback; // weak sitters only stagger them
@@ -280,7 +281,7 @@ export function updateZombies(dt) {
       if (!zb || zb.variant === 'r') continue; // side balls pass the boss; !zb: kills can sweep mid-loop
       if (Math.hypot(zb.x - e.x, zb.z - e.z) < (zb.variant === 'g' ? 0.75 : 0.55)) {
         if (zb.variant === 's' && e.vz < 0 && !(zb.shieldT > 0)) { zb.shieldT = TUNE.shieldDown; pock(0.9, 1800); } // chair blocks these too
-        else if (e.pow >= TUNE.zSplatQ) {
+        else if (e.pow >= TUNE.zSplatQ || zb.variant === 'f') {
           if (zb.variant === 'g' && --zb.hp > 0) splat(0.4); // wounds the brute
           else killZombie(j, !!G.horde);
         } else { zb.z -= TUNE.zPushback; pock(0.5, 300); }