feat: configurable keybindings for push-to-deafen and quick switcher

- Add deafenKey (default M) and quickSwitcherKey (default P) to settingsAtom
- Settings → Calls: Push to Deafen keybind tile using shared useKeyBind hook
- Settings → Keyboard Shortcuts: new section with Quick Room Switcher keybind
- Extract useKeyBind + keyLabel helpers to reduce duplication in Calls section
- CallControls reads deafenKey from settings (reactive, re-registers on change)
- ClientNonUIFeatures reads quickSwitcherKey from settings (same pattern)
- QuickSwitcher now toggles open/closed on repeat press (Ctrl+key again closes)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/features/call/CallControls.tsx

@@ -83,6 +83,7 @@ export function CallControls({ callEmbed }: CallControlsProps) {
   }, [shareConfirm]);
   const [pttMode] = useSetting(settingsAtom, 'pttMode');
   const [pttKey] = useSetting(settingsAtom, 'pttKey');
+  const [deafenKey] = useSetting(settingsAtom, 'deafenKey');
   const [lotusTerminal] = useSetting(settingsAtom, 'lotusTerminal');
   const [pttActive, setPttActive] = useState(false);
 
@@ -209,7 +210,7 @@ export function CallControls({ callEmbed }: CallControlsProps) {
       return false;
     };
     const onKeyDown = (e: KeyboardEvent) => {
-      if (e.code !== 'KeyM') return;
+      if (e.code !== deafenKey) return;
       if (e.repeat) return;
       if (isEditable(e.target as HTMLElement)) return;
       e.preventDefault();
@@ -217,7 +218,7 @@ export function CallControls({ callEmbed }: CallControlsProps) {
     };
     window.addEventListener('keydown', onKeyDown);
     return () => window.removeEventListener('keydown', onKeyDown);
-  }, [callEmbed]);
+  }, [callEmbed, deafenKey]);
 
   const [hangupState, hangup] = useAsyncCallback(
     useCallback(() => callEmbed.hangup(), [callEmbed]),