User notifications

[SIMULATAN]

Notify users when shit goes wrong
Like when the moodle token expired
Do it over a central service, post it there, save it to the DB, show it in a notification panel in the frontend
Optionally allow users to be notified over Discord, E-Mail, ... - maybe with a dedicated flow that receives notifications 👀
Will require "foreign" dedicated triggers - aka non-scheduled runs with specific inputs