Use frontmost application instead of running application.

I was having issues when trying to add a link from Safari using the hotkey.

When I looked into a bit, it was because I had Chrome running but no windows were open.  I quickly put this together and it fixed my issue.

After digging a bit deeper into the workflow, I noticed that it was calling pocket_save from the `fn` modifier key.  I'm not able to test that function at this time so if this breaks that functionality, I apologize and understand if you want to reject the request.