Sound: recorded SFX layer + a touch-easier CPU

Wire the new assets/audio/*.wav samples over the synth SFX:
- Ball hits: per-side tennis-player / tennis-opponent on serve & return,
  now with a stadium reverb tail (same convolver as umpire/aww).
- Crowd: tennis-applaus on your points/games (louder on big moments);
  tennis-aww when the opponent scores or you're eaten (reverb tail).
- Ambient bed: tennis-ambient-loop from first tap, 500Hz lowcut, low vol.
- Zombie music: zombie-mode loop when splatter kicks in (800Hz lowcut),
  fades out for the 1:1 sudden-death duel and back in after.
- Headshots: random headshot-1/-2 on every zombie kill (killZombie).

audio.js: sfx() one-shot player w/ rate+reverb opts, loopBed() beds with
duck/fade, aww() wrapper, hotter reverb send on the umpire voice.

Also: normal opponent aiFlub 0.09 -> 0.14 (a little easier to beat).

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

zombies.js

@@ -5,7 +5,7 @@
 
 import { TUNE, COURT } from './config.js';
 import { G, P, ball, sendBoy, setupPoint } from './state.js';
-import { splat, moan, pock, voice, boom, swish, shriek } from './audio.js';
+import { splat, moan, pock, voice, boom, swish, shriek, aww, sfx } from './audio.js';
 import { splatPoint, cheer, spentBall, resolveInterlude } from './gameplay.js';
 
 export const zombies = []; // {x, z, v, walkT, variant: 'a'|'b'|'c'}
@@ -64,6 +64,7 @@ function killZombie(i, quiet) {
     t: dark ? 0.6 + Math.random() * 0.6 : 0.4 + Math.random() * 0.4, dark,
   }); }
   splat();
+  sfx('headshot-' + (Math.random() < 0.5 ? 1 : 2), 0.6); // random headshot crack layered on the gore burst
   sendBoy(zb.x, zb.z);            // a boy sprints out to mop
   if (!G.horde) splatPoint('P', quiet); // a horde is survival — it doesn't score, so it can't chain into itself
 }
@@ -195,7 +196,7 @@ export function updateZombies(dt) {
         t: 0.5 + Math.random() * 0.5,
       });
       splat(1);
-      voice('game_set_massacre', 0.8);
+      voice('game_set_massacre', 0.8); aww(1); // the run is over — the crowd groans
       G.mode = 'eaten'; ball.active = false; G.flash = null; // zombies keep shambling for ambience
       G.horde = null; pellets.length = 0; extras.length = 0; G.mgT = 0; // everything stops; the eaten screen takes over
       try { // the run is over — settle it against the best (games survived, sets as tiebreak)