Fix: do not reject empty packets that arent message type (#510)

* do not reject empty packets that arent message type

* leave message with empty byte array

* clean up comments

app/src/main/java/com/bitchat/android/mesh/BluetoothMeshService.kt

@@ -949,12 +949,11 @@ class BluetoothMeshService(private val context: Context) {
      * Send leave announcement
      */
     private fun sendLeaveAnnouncement() {
-        val nickname = delegate?.getNickname() ?: myPeerID
         val packet = BitchatPacket(
             type = MessageType.LEAVE.value,
             ttl = MAX_TTL,
             senderID = myPeerID,
-            payload = nickname.toByteArray()
+            payload = byteArrayOf()
         )
         
         // Sign the packet before broadcasting