Horde: spawn all zombies from the far baseline, not the sides

The x=±6 side spawns forced you to machine-gun targets off the edge of
your view/pellet lane. Now every horde zombie enters from the far
baseline across the court like the normal spawns, so the whole swarm
comes down in front of you.

Verified via window.T: a full 12s horde spawns ~29 zombies, all at the
far baseline (z -1.5..-2.5, |x| ≤ 4.9), zero side spawns.

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

zombies.js

@@ -79,9 +79,8 @@ function splatter(i, fanfare = true) { // the MAIN ball hit a zombie
 }
 
 // ---- horde wave: dense spawns + an auto-firing machine-gun racket (pellets, not the match ball)
-function spawnHordeZombie() {
+function spawnHordeZombie() { // all from the far baseline, across the court — never off-screen at the sides
-  if (Math.random() < 0.5) spawnZombie((Math.random() * 2 - 1) * 5, -1.5 - Math.random(), Math.random() < 0.5 ? 'a' : 'b'); // far baseline
+  spawnZombie((Math.random() * 2 - 1) * 5, -1.5 - Math.random(), Math.random() < 0.5 ? 'a' : 'b');
-  else spawnZombie(Math.random() < 0.5 ? -6 : 6, Math.random() * 8, Math.random() < 0.5 ? 'a' : 'b');                       // in from the sides
 }
 function firePellet() {
   const a = (Math.random() * 2 - 1) * 4 * Math.PI / 180, s = 26; // ±4° spread, straight up-court (-z)