fix: clear task after linking device to prevent going back and treating PNModeActivity.kt viewing as seeing welcome screen so the fallback notifications will be used and allow users through without selecting PN type

app/src/main/java/org/thoughtcrime/securesms/loki/activities/LinkDeviceActivity.kt

@@ -115,7 +115,10 @@ class LinkDeviceActivity : BaseActionBarActivity(), ScanQRCodeWrapperFragmentDel
 
     private fun register(skipped: Boolean) {
         restoreJob?.cancel()
+        loader.isVisible = false
+        ApplicationContext.getInstance(this).stopPolling()
         val intent = Intent(this@LinkDeviceActivity, if (skipped) DisplayNameActivity::class.java else PNModeActivity::class.java)
+        intent.flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
         push(intent)
     }
     // endregion

app/src/main/java/org/thoughtcrime/securesms/loki/activities/PNModeActivity.kt

@@ -33,6 +33,7 @@ class PNModeActivity : BaseActionBarActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setUpActionBarSessionLogo()
+        TextSecurePreferences.setHasSeenWelcomeScreen(this, true)
         setContentView(R.layout.activity_pn_mode)
         contentView.disableClipping()
         fcmOptionView.setOnClickListener { toggleFCM() }
@@ -150,7 +151,6 @@ class PNModeActivity : BaseActionBarActivity() {
             dialog.create().show()
             return
         }
-        TextSecurePreferences.setHasSeenWelcomeScreen(this, true)
         TextSecurePreferences.setIsUsingFCM(this, (selectedOptionView == fcmOptionView))
         val application = ApplicationContext.getInstance(this)
         application.setUpStorageAPIIfNeeded()