rfc: Support for Push notifications

[Garrythepro]

Dupe Check

• I have searched Swetrix feature requests and there are no duplicates

Describe the solution you'd like?

Support for web hook based push notifications via services like ntfy.
Usually Swetrix should send a notification request to ntfy server, then the ntfy server sends the push notification to the ntfy app, or to any app that is configured to use the ntfy service.
Benefit is that alerts from Swetrix can come in a custom app if required.
Beszel (server monitoring) and Uptime Kuma (uptime monitoring) are two examples.

Additional context

No response

How important is this feature to you?

3