explicit leave when disconnect requested, stop all tracks, including remote

@@ -205,8 +205,15 @@ constructor(
 
         sendRequest(request)
     }
+    
+    fun sendLeave() {
+        val request = LivekitRtc.SignalRequest.newBuilder()
+            .setLeave(LivekitRtc.LeaveRequest.newBuilder().build())
+            .build()
+        sendRequest(request)
+    }
 
-    fun sendRequest(request: LivekitRtc.SignalRequest) {
+    private fun sendRequest(request: LivekitRtc.SignalRequest) {
         Timber.v { "sending request: $request" }
         if (!isConnected || currentWs == null) {
             throw IllegalStateException("not connected!")

@@ -66,6 +66,7 @@ constructor(
     }
 
     fun disconnect() {
+        engine.client.sendLeave()
         handleDisconnect()
     }
 
@@ -137,8 +138,14 @@ constructor(
     }
 
     private fun handleDisconnect() {
-        for (track in localParticipant?.tracks.values) {
-            track.track?.stop()
+        for (pub in localParticipant.tracks.values) {
+            pub.track?.stop()
+        }
+        // stop remote tracks too
+        for (p in remoteParticipants.values) {
+            for (pub in p.tracks.values) {
+                pub.track?.stop()
+            }
         }
         engine.close()
         state = State.DISCONNECTED