Revert splatter rapid-fire serve; fix horde pose + re-trigger

Oliver's feedback on the feel pass:

1. Rapid-fire serving was way too easy. Reverted splatter serving to the
   proper model: a tap does the toss ritual (apex timing = quality), a
   flick is a quick aimed serve. Dropped the multi-ball barrage and
   removed the extraBalls plumbing (array, update, render, hooks). Melee
   swish and zombie homing stay. If multi-ball is wanted back, it should
   require a proper serve per ball.
2. The player was stuck in the serve/swing pose when a horde started
   (the triggering shot's pose lingered) — startHorde now clears it.
3. A horde re-triggered immediately: machine-gun kills scored points, so
   games were won mid-horde and the next kill after it ended won another
   game → instant new horde. A horde is now survival: it doesn't score
   (splatPoint skipped while G.horde), so it can't chain. After a horde
   you must win a full game again to summon the next.

Verified via window.T: a tap tosses (not an instant serve) and the full
toss→serve→rally completes; melee still kills adjacent shamblers; pose is
idle/-1 at horde start; no scoring during a horde and the next kill after
scores 15 without restarting it; tennis 11/12, bomb consume, homing all
still green; no console errors.

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

zombies.js

@@ -13,7 +13,6 @@ export const gore = [];    // lawn decals {x, z, r, a}  — the flat ground laye
 export const piles = [];   // 3D-ish gore mounds {x, z, size 1..4, seed} — grow where kills cluster
 export const parts = [];   // splatter particles {x, y, z, vx, vy, vz, t, dark}
 export const pellets = []; // machine-gun rounds during a horde {x, y, z, vx, vz, t}
-export const extraBalls = []; // earlier serves still in flight while you fire the next {x,y,z,vx,vy,vz,g,pow,bomb,bounces}
 
 let spawnT = 1.5, moanT = 3;
 
@@ -40,7 +39,7 @@ function killZombie(i, quiet) {
   }); }
   splat();
   sendBoy(zb.x, zb.z);            // a boy sprints out to mop
-  splatPoint('P', quiet);        // horde kills rate-limit the umpire so he doesn't machine-gun scores
+  if (!G.horde) splatPoint('P', quiet); // a horde is survival — it doesn't score, so it can't chain into itself
 }
 
 // swishing the racket cleaves any shambler in reach (the racket-zombie boss shrugs melee off)
@@ -54,14 +53,6 @@ export function meleeSwipe(x, z, range) {
   return hit;
 }
 
-// serving again while a ball still flies: stash the current one so it keeps killing (a barrage)
-export function stashExtraBall() {
-  if (!ball.active) return;
-  extraBalls.push({ x: ball.x, y: ball.y, z: ball.z, vx: ball.vx, vy: ball.vy, vz: ball.vz,
-    g: ball.g, pow: ball.pow, bomb: ball.bomb, bounces: ball.bounces });
-  if (extraBalls.length > 6) extraBalls.shift(); // cap the barrage
-}
-
 function splatter(i, fanfare = true) { // the MAIN ball hit a zombie
   killZombie(i, !!G.horde);
   ball.vx *= TUNE.zPierce; ball.vz *= TUNE.zPierce; // keep enough pace to plow through the next
@@ -150,7 +141,7 @@ export function updateZombies(dt) {
       splat(1);
       voice('game_set_massacre', 0.8);
       G.mode = 'eaten'; ball.active = false; G.flash = null; // zombies keep shambling for ambience
-      G.horde = null; pellets.length = 0; extraBalls.length = 0; // the swarm stops; the eaten screen takes over
+      G.horde = null; pellets.length = 0;                    // the swarm stops; the eaten screen takes over
     }
     if (ball.active && ball.lastHit === 'P' && ball.y < 1.9) {
       const d = Math.hypot(ball.x - zb.x, ball.z - zb.z);
@@ -165,7 +156,7 @@ export function updateZombies(dt) {
         ball.vx *= 0.6; ball.vz *= 0.6; ball.lastHit = 'X'; // spent — one stagger per ball
       }
     }
-    if (zb.z >= COURT.L + 0.7) { zombies.splice(i, 1); if (G.mode !== 'eaten') splatPoint('O', !!G.horde); } // it reached your baseline
+    if (zb.z >= COURT.L + 0.7) { zombies.splice(i, 1); if (G.mode !== 'eaten' && !G.horde) splatPoint('O'); } // it reached your baseline
   }
 
   for (let i = pellets.length - 1; i >= 0; i--) { // machine-gun rounds: flat, fast, one-shot kills
@@ -177,22 +168,6 @@ export function updateZombies(dt) {
     if (hit || pe.t <= 0) pellets.splice(i, 1);
   }
 
-  for (let i = extraBalls.length - 1; i >= 0; i--) { // earlier serves keep arcing and killing
-    const b = extraBalls[i];
-    b.vy -= (b.g || TUNE.gravity) * dt;
-    b.x += b.vx * dt; b.y += b.vy * dt; b.z += b.vz * dt;
-    let done = false;
-    if (b.y <= 0 && b.vy < 0) { b.y = 0; b.vy = -b.vy * TUNE.bounceY; b.vx *= TUNE.bounceXZ; b.vz *= TUNE.bounceXZ; b.bounces++;
-      if (b.bomb) { explode(b.x, b.z); done = true; } }
-    if (!done && b.y < 1.9) for (let j = zombies.length - 1; j >= 0; j--) {
-      if (zombies[j].variant === 'r' || Math.hypot(zombies[j].x - b.x, zombies[j].z - b.z) >= 0.55) continue;
-      if (b.bomb) { explode(b.x, b.z); done = true; }
-      else if ((b.pow || 0) >= TUNE.zSplatQ) { killZombie(j, !!G.horde); b.vx *= TUNE.zPierce; b.vz *= TUNE.zPierce; }
-      break;
-    }
-    if (done || b.bounces >= 2 || b.z < -2 || b.z > 25.5 || Math.abs(b.x) > 7.5) extraBalls.splice(i, 1);
-  }
-
   for (let i = parts.length - 1; i >= 0; i--) {
     const p = parts[i];
     p.t -= dt; p.vy -= 14 * dt;