fix(chat): react to MediaController disconnection in ChatActivity

Add a MediaController.Listener to detect onDisconnected, e.g. when the
VoiceMessageMediaService/MediaSession dies unexpectedly while the chat
is still visible. Without this, mediaController would be left as a
stale reference and the UI (play button, seekbar polling) could get
stuck instead of resetting.

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

@@ -1400,7 +1400,15 @@ class ChatActivity :
         this.lifecycle.addObserver(chatViewModel)
 
         val sessionToken = SessionToken(this, ComponentName(this, VoiceMessageMediaService::class.java))
-        val future = MediaController.Builder(this, sessionToken).buildAsync()
+        val future = MediaController.Builder(this, sessionToken)
+            .setListener(object : MediaController.Listener {
+                override fun onDisconnected(controller: MediaController) {
+                    mediaController?.removeListener(playerListener)
+                    stopProgressPolling()
+                    mediaController = null
+                }
+            })
+            .buildAsync()
         mediaControllerFuture = future
 
         future.addListener({