Based on the interval a user picks, pass budget info to NWC when creating the connection. That way, the user does not need to set it up. Use the delay in milliseconds to figure out which interval makes sense (daily, weekly, monthly, yearly) and set the correct amount of sats to be exactly needed.
Also, make it impossible to create subscriptions with an interval more than 1 year (there is no point in this).
The change needs to be made here: https://github.com/getAlby/ZapPlanner/blob/main/app/confirm/components/ConfirmSubscriptionForm.tsx#L60