[enhancement] support recurring tasks

[throwaway-nolsh]

first off, this is literally exactly what i was looking for as a calendar, so thank you immensely for putting this out there, i love it and if i had more experience coding typescript id absolutely do some pr's (will probably contribute in the future)

that said, id really like recurring tasks to be supported, at least the simple format of 🔁 every year or month or something similar.

this would be great for adding birthdays to the calendar

thanks :)