Feature: Referral System (Recruit Friends for Credits)

Invite friends to 6502ish and get paid for every signup.

Where: /recruit

How to use:

1. Visit the Recruit page — your unique referral link is shown (like https://6502ish.com/join/abc123def).
2. Share the link (email, Discord, Mastodon, BBS sig file, whatever).
3. When someone registers through your link, you earn 500 credits and get a notification.

Recruitment achievements stack on top of the credits:

• first_recruit (1) — +250
• five_recruits (5) — +250
• ten_recruits (10) — +250
• twenty_recruits (20) — +250
• fifty_recruits (50) — +250
• hundred_recruits (100) — +250

Tracking: your recruit dashboard shows click count, signup count, and a running credits total. The leaderboard at /leaderboard has a top-recruiters section.