Add Referral Program API

[Olowodarey]

Description:
Implement a referral system where users can invite friends and earn rewards when referrals complete their first deposit.

Acceptance Criteria:

• Generate unique referral codes per user
• Track referral signups and conversions
• Reward calculation and distribution
• GET /referrals/stats for user's referral dashboard
• Admin API for managing referral campaigns
• Fraud detection for referral abuse
• Integration with notification system

Database Schema:

CREATE TABLE referrals (
  id UUID PRIMARY KEY,
  referrer_id UUID REFERENCES users(id),
  referee_id UUID REFERENCES users(id),
  referral_code VARCHAR(20) UNIQUE,
  status VARCHAR(20), -- pending, completed, rewarded
  reward_amount DECIMAL(18, 7),
  created_at TIMESTAMP,
  completed_at TIMESTAMP
);

[Zarmaijemimah]

@Zarmaijemimah has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

I can handle this issue and I will love to work on it please kindly assign thank you.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Zarmaijemimah to this issue.

[drips-wave]

Congratulations, @Zarmaijemimah! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on March 30, 2026.

🧑‍💻 @Zarmaijemimah: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

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🌊 Happy Wave 🌊

[drips-wave]

This issue has been completed by @Zarmaijemimah as part of the Stellar Wave Program's 3rd Wave 🥳

😎 @Zarmaijemimah: You earned 200 Points for completing this issue! After the current Wave ends, you'll be eligible for a percentage of the Wave's reward pool based on the percentage of total points you've earned. Learn more here. You can also Leave a review to share your experience working on this issue.

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