Give the machine, fire, gun and boss their missing sounds

All four synthesized in audio.js like every other weapon: a squeaking
castor, a court-wide crackle clock plus a throttled catch, a real gun
crack, and one shared boss voice (stomp per stride, wind-up breath,
bark, pain, death roar) pitched by body size. Closes OPEN 13 pending
the phone verdict. v355.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

index.html

@@ -1140,6 +1140,6 @@ if (location.hostname !== 'splatter-tennis.wuwi.one' && !window.Capacitor?.isNat
   </div>
 </div>
 <span id="recLamp" hidden>REC</span>
-<script type="module" src="src/main.js?v=354"></script>
+<script type="module" src="src/main.js?v=355"></script>
 </body>
 </html>