set = (key, value) => {
  store.set(key, value)
  if (ipcRenderer) {
    console.log('notify main process', key, value)
    // Notify main process about settings changes
    ipcRenderer.send('updateSettings', key, value)
  }
}
Write a value to global config. It immedately rewrites global config
and notifies all listeners about changes

@param  {String} key
@param  {Any} value