fix(chat): avoid main-thread deadlock in ChatActivity onStart media controller connect

The onStart() listener re-read the mutable mediaControllerFuture field
instead of the future it was registered against. If onStart() ran again
before a prior connection attempt's listener fired, that listener could
end up blocking get() on a newer, not-yet-completed future, deadlocking
the main thread and causing an ANR. Capture the future in a local val
and ignore the callback if it's no longer the current connection attempt.

Assisted-by: Claude Code:claude-sonnet-5

Signed-off-by: Marcel Hibbe <dev@mhibbe.de>

Author: mahibi

app/src/main/java/com/nextcloud/talk/chat/ChatActivity.kt

@@ -1400,11 +1400,16 @@ class ChatActivity :
         this.lifecycle.addObserver(chatViewModel)
 
         val sessionToken = SessionToken(this, ComponentName(this, VoiceMessageMediaService::class.java))
-        mediaControllerFuture = MediaController.Builder(this, sessionToken).buildAsync()
+        val future = MediaController.Builder(this, sessionToken).buildAsync()
+        mediaControllerFuture = future
+
+        future.addListener({
+            if (future !== mediaControllerFuture) {
+                return@addListener
+            }
 
-        mediaControllerFuture?.addListener({
             mediaController = try {
-                mediaControllerFuture?.get()
+                future.get()
             } catch (_: CancellationException) {
                 null
             }