feat: mute screenshare audio independently + fix CI lint/prettier

- Add screenshareAudioMuted state to CallControlState and CallControl
- setSound() now preserves screenshare audio mute when un-deafening
- Add toggleScreenshareAudio() targeting audio[data-lk-source="screen_share_audio"]
- Add ScreenshareAudioButton (volume icon, warns when muted) to controls bar
- Fix unused prevScreenshare variable (ESLint error from prior commit)
- Run Prettier on Controls.tsx and CallControl.ts (CI formatting failures)

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

src/app/features/call/CallControls.tsx

@@ -24,6 +24,7 @@ import {
   FullscreenButton,
   MicrophoneButton,
   ScreenShareButton,
+  ScreenshareAudioButton,
   SoundButton,
   VideoButton,
 } from './Controls';
@@ -67,9 +68,8 @@ export function CallControls({ callEmbed }: CallControlsProps) {
     }
   }, [callEmbedRef]);
 
-  const { microphone, video, sound, screenshare, spotlight } = useCallControlState(
-    callEmbed.control,
-  );
+  const { microphone, video, sound, screenshare, spotlight, screenshareAudioMuted } =
+    useCallControlState(callEmbed.control);
 
   const [cords, setCords] = useState<RectCords>();
   const [shareConfirm, setShareConfirm] = useState(false);
@@ -346,6 +346,10 @@ export function CallControls({ callEmbed }: CallControlsProps) {
               onToggle={() => callEmbed.control.toggleMicrophone()}
             />
             <SoundButton enabled={sound} onToggle={() => callEmbed.control.toggleSound()} />
+            <ScreenshareAudioButton
+              muted={screenshareAudioMuted}
+              onToggle={() => callEmbed.control.toggleScreenshareAudio()}
+            />
           </Box>
           {!compact && <ControlDivider />}
           <Box shrink="No" alignItems="Inherit" justifyContent="Inherit" gap="200">