fix(audio-rooms): unwrap hiddenUsers State for the feed key (audit walk #9)

Pre-existing bug surfaced during the user-walkthrough audit:
WatchAccountForAudioRoomsScreen used `val hiddenUsers =
hiddenUsers.flow.collectAsStateWithLifecycle()` (no `by`), so the
LaunchedEffect captured a State<T> object as a key rather than
the unwrapped value. State equality is reference-based and the
remembered State instance is stable across recompositions, so the
effect never re-fired when the user muted someone — the rooms
feed showed stale results until a manual refresh.

Switching to `val hiddenUsers by ...` unwraps the value so
LaunchedEffect re-keys when the hidden-users set changes.

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/audiorooms/AudioRoomsScreen.kt

@@ -133,9 +133,13 @@ fun WatchAccountForAudioRoomsScreen(
     accountViewModel: AccountViewModel,
 ) {
     val listState by accountViewModel.account.liveLiveStreamsFollowLists.collectAsStateWithLifecycle()
-    val hiddenUsers =
-        accountViewModel.account.hiddenUsers.flow
-            .collectAsStateWithLifecycle()
+    // Use `by` to unwrap the StateFlow's value into the LaunchedEffect
+    // key — without it, the State<T> object is reference-stable across
+    // recompositions and the effect never re-fires when the user
+    // mutes someone, leaving the rooms feed stale until a manual
+    // refresh.
+    val hiddenUsers by accountViewModel.account.hiddenUsers.flow
+        .collectAsStateWithLifecycle()
 
     LaunchedEffect(accountViewModel, listState, hiddenUsers) {
         audioRoomsFeedState.checkKeysInvalidateDataAndSendToTop()