Automatic invoice notifications

[WoofWolfGG]

Hi! The new invoice system is great, thank you!
I would like to add a small thing to it, namely - notifications about unpaid invoices every time you log in to the server (and maybe a configurable notification, e.g. once an hour)

[zefir-git]

Hi! For manual notifications, you can use /invoice send.

When logging in, would this be something like a "You have 123 unpaid invoices [click to view]" message?

[WoofWolfGG]

Yeah, something like that