Start at login on Linux

The app works on Linux, but the right click on top of the icon does not display the list of menus. This is a [known Electron limitation](https://electronjs.org/docs/api/tray#traypopupcontextmenumenu-position-macos-windows).

I expect this problem to be solved by an external npm package. If said package carries more than needed I suggest to learn its implementation and do the same here while referring and acknowledging the work of the original package.

P.S.: [startup.js](https://github.com/antonio-ramadas/palbum/blob/7fb451b6567a8e3d1b929e7a3a4c06b5ed2a8b5f/public/startup.js) details this problem to a great extent.