feat(lotus): screenshare tile speaker glyph reflects real audio state (#38)

The spotlight screenshare tile already shows a speaker glyph only when the
share publishes audio. Two gaps: a publication the sharer had muted still
counted as audio, and the host's screenshare-audio mute (io.lotus.set_deafen
→ renderer muted) wasn't reflected — the glyph stayed "on" while nothing
played. audioEnabled$ now tracks publication presence AND !isMuted via
observeParticipantMedia; the glyph shows crossed when either the tile's
own mute or the Lotus mute is active.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/state/media/RemoteScreenShareViewModel.ts

@@ -7,7 +7,7 @@ Please see LICENSE in the repository root for full details.
 */
 
 import { Track, type RemoteParticipant } from "livekit-client";
-import { map, of, switchMap } from "rxjs";
+import { distinctUntilChanged, map, of, switchMap } from "rxjs";
 
 import { type Behavior } from "../Behavior";
 import {
@@ -17,7 +17,7 @@ import {
 } from "./ScreenShareViewModel";
 import { type ObservableScope } from "../ObservableScope";
 import { createVolumeControls, type VolumeControls } from "../VolumeControls";
-import { observeTrackReference$ } from "../observeTrackReference";
+import { observeParticipantMedia } from "@livekit/components-core";
 
 export interface RemoteScreenShareViewModel
   extends BaseScreenShareViewModel, VolumeControls {
@@ -58,14 +58,24 @@ export function createRemoteScreenShare(
     videoEnabled$: scope.behavior(
       pretendToBeDisconnected$.pipe(map((disconnected) => !disconnected)),
     ),
+    // [lotus #38] "Has audio" means the sharer publishes screenshare audio AND
+    // hasn't muted it — a muted publication would show a speaker glyph for a
+    // share nobody can hear.
     audioEnabled$: scope.behavior(
       inputs.participant$.pipe(
         switchMap((p) =>
           p
-            ? observeTrackReference$(p, Track.Source.ScreenShareAudio)
-            : of(null),
+            ? observeParticipantMedia(p).pipe(
+                map(() => {
+                  const pub = p.getTrackPublication(
+                    Track.Source.ScreenShareAudio,
+                  );
+                  return !!pub && !pub.isMuted;
+                }),
+              )
+            : of(false),
         ),
-        map(Boolean),
+        distinctUntilChanged(),
       ),
     ),
   };