feat(call): mute + deafen global hotkeys with chord support (group E)

- New voiceHotkeys.ts storage module. Stores per-action bindings with
  modifier flags (Ctrl/Shift/Alt) so Discord-style chords like
  Ctrl+Shift+M work. Defaults match Discord — Ctrl+Shift+M mute,
  Ctrl+Shift+D deafen — but ship disabled to avoid surprise collisions.
- globalShortcut.ts grows registerGlobalShortcutPress /
  unregisterGlobalShortcut helpers that accept pre-formatted Tauri
  accelerator strings, since voiceHotkey chords can't be expressed by
  the existing codeToShortcut path (PTT-only single-key).
- CallContext registers the chords OS-wide while a call is active
  (connected | reconnecting) so the hotkeys work from any focused
  window. A window-keydown fallback handles the non-Tauri / denied
  registration case. Both unregister on call end.
- SettingsPage adds VoiceHotkeyControls (mute + deafen variants)
  with a chord-capture button that waits past modifier-only presses
  and binds to the first real key. Labels render as "Ctrl+Shift+M"
  consistently with the in-call PTT hint.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/desktop/src/pages/SettingsPage.tsx

@@ -25,6 +25,13 @@ import {
   subscribePttSettings,
   updatePttSettings,
 } from '../lib/pttSettings';
+import {
+  getVoiceHotkeys,
+  subscribeVoiceHotkeys,
+  updateVoiceHotkey,
+  type VoiceHotkeyKind,
+  type VoiceHotkeys,
+} from '../lib/voiceHotkeys';
 import {
   AUDIO_QUALITY_ORDER,
   type AudioQuality,
@@ -163,6 +170,12 @@ export function SettingsPage() {
         <div className="mt-3 border-t border-line pt-3">
           <PttControls />
         </div>
+        <div className="mt-3 border-t border-line pt-3">
+          <VoiceHotkeyControls kind="mute" />
+        </div>
+        <div className="mt-3 border-t border-line pt-3">
+          <VoiceHotkeyControls kind="deafen" />
+        </div>
         <div className="mt-3 border-t border-line pt-3">
           <CallE2EEControls />
         </div>
@@ -263,6 +276,96 @@ function PttControls() {
   );
 }
 
+function VoiceHotkeyControls({ kind }: { kind: VoiceHotkeyKind }) {
+  const { t } = useTranslation(['app']);
+  const [hotkeys, setHotkeys] = useState<VoiceHotkeys>(() => getVoiceHotkeys());
+  const [capturing, setCapturing] = useState(false);
+
+  useEffect(() => subscribeVoiceHotkeys(setHotkeys), []);
+
+  useEffect(() => {
+    if (!capturing) return;
+    const onKey = (e: KeyboardEvent) => {
+      // Modifier-only presses shouldn't bind — wait for a real key to
+      // arrive. Escape aborts the capture.
+      if (e.code === 'Escape') {
+        e.preventDefault();
+        setCapturing(false);
+        return;
+      }
+      if (
+        e.code === 'ControlLeft' ||
+        e.code === 'ControlRight' ||
+        e.code === 'ShiftLeft' ||
+        e.code === 'ShiftRight' ||
+        e.code === 'AltLeft' ||
+        e.code === 'AltRight' ||
+        e.code === 'MetaLeft' ||
+        e.code === 'MetaRight'
+      ) {
+        return;
+      }
+      e.preventDefault();
+      updateVoiceHotkey(kind, {
+        key: e.code,
+        ctrl: e.ctrlKey || e.metaKey,
+        shift: e.shiftKey,
+        alt: e.altKey,
+      });
+      setCapturing(false);
+    };
+    window.addEventListener('keydown', onKey, { capture: true });
+    return () => window.removeEventListener('keydown', onKey, { capture: true });
+  }, [capturing, kind]);
+
+  const binding = hotkeys[kind];
+  const toggleLabel =
+    kind === 'mute'
+      ? t('app:settings.hotkey_mute_enabled', { defaultValue: 'Mute-Hotkey' })
+      : t('app:settings.hotkey_deafen_enabled', { defaultValue: 'Deafen-Hotkey' });
+  const toggleHint =
+    kind === 'mute'
+      ? t('app:settings.hotkey_mute_hint', {
+          defaultValue:
+            'Schaltet dein Mikro an/aus — funktioniert auch wenn ChatApp im Hintergrund ist.',
+        })
+      : t('app:settings.hotkey_deafen_hint', {
+          defaultValue:
+            'Schaltet eingehendes Audio + dein Mikro stumm (wie in Discord).',
+        });
+
+  return (
+    <>
+      <Toggle
+        label={toggleLabel}
+        hint={toggleHint}
+        checked={binding.enabled}
+        onChange={(v) => updateVoiceHotkey(kind, { enabled: v })}
+      />
+      <SettingRow
+        label={t('app:settings.hotkey_binding', { defaultValue: 'Hotkey' })}
+      >
+        <button
+          type="button"
+          onClick={() => setCapturing((v) => !v)}
+          className={
+            'inline-flex min-w-[10rem] cursor-pointer items-center justify-center rounded-lg border px-3 py-1.5 text-xs font-mono font-semibold transition focus:outline-none focus-visible:ring-2 focus-visible:ring-accent/40 ' +
+            (capturing
+              ? 'border-accent bg-accent/20 text-fg animate-pulse'
+              : 'border-line bg-surface-3 text-fg hover:brightness-95')
+          }
+        >
+          {capturing
+            ? t('app:settings.hotkey_press_combo', {
+                defaultValue: 'Kombination drücken…',
+              })
+            : binding.keyLabel}
+        </button>
+      </SettingRow>
+    </>
+  );
+}
+
 function CallE2EEControls() {
   const { t } = useTranslation(['app']);
   const [cfg, setCfg] = useState<CallE2EESettings>(() => getCallE2EESettings());