gui: add persistent notification and run NfdService in foreground to improve stability

Change-Id: I47e7ff07888e4638a75ddb607d335511467a7779
refs: #4766
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 51c923b..9705135 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -10,6 +10,7 @@
     <uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE" />
     <uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
 
     <application
         android:allowBackup="true"