Support multi-tier (multi-level) referral rewards

[Abidoyesimze]

src/referral/service.ts is explicitly documented as a single-level program: a referrer earns a reward when someone they referred activates, full stop. There's no second tier — the referrer's own referrer earns nothing from a sub-referral.

Task

• Add an optional second-tier reward (referrer's-referrer gets a smaller reward on the same activation event) behind a config flag, without disturbing the existing PENDING → ACTIVATED → REWARDED lifecycle or the transactional activation check in checkAndActivateOnDeposit.
• The payout job (jobs/referralPayout.ts) should pay all eligible tiers in the same sweep.
• Add tests for a 2-tier chain, including the case where the tier-2 referrer's own code is no longer active.

[samuelfrancis163-eng]

@samuelfrancis163-eng has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hello, I'd like to work on this issue because i am confident i can deliver smoothly, Please assign issue to me ETA 3 HOURS

ℹ️ Repo Maintainers: To accept this application, review their application or assign @samuelfrancis163-eng to this issue.

[AzahasTech]

@AzahasTech has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi! I’d like to work on this issue.
I’ve worked on similar tasks across different stacks and I’m comfortable contributing within existing architectures and project conventions. I’ll make sure the implementation is clean, tested, and aligned with the requirements outlined in the issue.

Thanks!

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

[dadadave80]

@dadadave80 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

I'd like to work on this

ℹ️ Repo Maintainers: To accept this application, review their application or assign @dadadave80 to this issue.

[drips-wave]

Congratulations, @dadadave80! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

🧑‍💻 @dadadave80: 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

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@dadadave80's PR #411 was approved and merged by @Abidoyesimze.

🏆 @dadadave80: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (118 total points). Track your full progress on GrantFox.

👏 Great work, @dadadave80! Keep contributing to Neurowealth.

[drips-wave]

This issue has been completed by @dadadave80 as part of the Stellar Wave Program's 8th Wave 🥳

😎 @dadadave80: 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.

🧑‍💻 Repo maintainers: How'd the contributor do? Leave a review to share your experience working with them.