Operator battle voices: the official combat lines play by voice slot during battles, one at a time (#73)

Deploy, skill and result lines come from the operators' official voice slots; a newer line takes the channel over (stale callbacks of the replaced line no longer release it), and the result line is spoken by an operator of the player's own battle. Contributed by @Convey123.

public/js/ui/settings.js

@@ -1,4 +1,4 @@
-// Player settings (BGM/SFX volume, mute, damage numbers, render quality): a tiny observable store
+// Player settings (BGM/SFX/voice volume, mute, damage numbers, render quality): a tiny observable store
 // persisted in localStorage (`sp.pref.settings`), applied to the audio manager on every change, plus
 // the settings modal.
 
@@ -10,7 +10,7 @@ import { audio } from '../audio.js';
 import { openGuide } from './guide.js';
 import { detectFeatures } from './device.js';
 
-/** Settings store: { bgm, sfx, muted, damageNumbers, quality }. */
+/** Settings store: { bgm, sfx, voice, muted, damageNumbers, quality }. */
 export const settingsStore = createStore(sanitizeSettings(loadPref('settings', null)));
 
 settingsStore.subscribe((s) => {
@@ -60,6 +60,7 @@ export function SettingsModal({ open, onClose }) {
       <${Button} variant="primary" icon="check" onClick=${onClose}>完成<//>`}>
     <div class="set-list">
       <${Slider} label="背景音乐" micro="BGM" icon="play" value=${s.bgm} onInput=${(v) => updateSettings({ bgm: v })} />
+      <${Slider} label="干员语音" micro="VOICE" icon="mic" value=${s.voice} onInput=${(v) => updateSettings({ voice: v })} />
       <${Slider} label="音效" micro="SFX" icon="signal" value=${s.sfx}
         onInput=${(v) => { updateSettings({ sfx: v }); if (!tested) { setTested(true); setTimeout(() => setTested(false), 400); audio.sfx('click'); } }} />
       <${Toggle} label="静音" micro="MUTE" value=${s.muted} onChange=${(v) => updateSettings({ muted: v })} />