Referral program during registration

We need to create a referral program for the applications, this would be especially good for Connected but probably won't have the time to get there.

@pholm @Earlo I'd love your input on this. How I imagine it:

* User clicks register to the event
* User fills in information
* User sees "Refer 10 friends and secure your spot in hub"
* User refers friend, and when friend registers -> User gets point -> 10 points earn a secured spot

Comments?

Start by reviewing the registration flow in JunctionApp and clarify whether the referral program applies to all applications or specifically Connected. Define the referral, friend-registration, point, and secured-spot rules before identifying implementation entry points. Done means the agreed flow is implemented and verified across registration and referral cases.

Scritto dal modello di indicizzazione a partire dal testo della issue.