Custom shell command / script as a schedule task

[Asnardd]

Right now the schedule system only has a handful of fixed tasks like send command, create backup, toggle power. That covers most a lot of simple cases but leaves out anything custom, like syncing backups to an external location, running a cleanup script, or any maintenance task specific to one's setup

My use case: I have Pelican running Minecraft servers, and I want a scheduled task that rsyncs the backups Pelican creates over to my NAS. There's no way to do that from the panel today, I've had to set up a separate cron on the host which kind of defeats the point of having schedule management in the panel and having everything maintenance related on the panel

I'm not asking for a full scripting language because that was already discussed in #154 and I get why that's not the direction
What I'm thinking is simpler: just a "run shell command" task type, maybe admin/root only or behind a feature flag, similar to how Pelican already gates sensitive functionalities. Something like what pterodactyl/panel#3008 originally proposed before it got closed
Would make a lot of self-hosted setups a lot more self-contained, and a big addition for customization