fix: local stream video visibility and audio double-playback

Show local user's own screen share in their stream tile by bypassing
the isSubscribed check for local participants and auto-watching/unwatching
local streams on publish/unpublish. Eliminate audio double-playback by
detaching LiveKit's auto-attached audio elements so GlobalAudioRenderer
is the sole playback path, making attenuation and volume controls effective.
Fix GainNode leak in useAudioTrackPlayer cleanup paths.

packages/web/src/hooks/useAudioTrackPlayer.js

@@ -71,10 +71,13 @@ export function useAudioTrackPlayer(opts) {
         else {
             // --- STANDARD MODE (0% - 100%) ---
             // Clean up boost pipeline if it exists
+            if (boostGainRef.current) {
+                boostGainRef.current.disconnect();
+                boostGainRef.current = null;
+            }
             if (boostSourceRef.current) {
                 boostSourceRef.current.disconnect();
                 boostSourceRef.current = null;
-                boostGainRef.current = null;
             }
             audioEl.muted = false;
             audioEl.volume = Math.min(volume, 1.0);
@@ -84,10 +87,13 @@ export function useAudioTrackPlayer(opts) {
             }
         }
         return () => {
+            if (boostGainRef.current) {
+                boostGainRef.current.disconnect();
+                boostGainRef.current = null;
+            }
             if (boostSourceRef.current) {
                 boostSourceRef.current.disconnect();
                 boostSourceRef.current = null;
-                boostGainRef.current = null;
             }
         };
     }, [volume, muted, track]);