Unvalidated Referrer identity in place_bet

[hman38705]

Description
The referrer parameter in place_bet is accepted as an Option<Address> (Line 19). There is zero validation that the provided address is a valid user or not the bettor themselves (redundant with Issue 21/601). Furthermore, there is no check that the referrer hasn't been banned or blacklisted by the protocol.

Requirements and context

• Implement formal referrer verification.
• Ensure the referrer is an active and authorized participant.

Suggested execution

• Fork the repo and create a branch: git checkout -b fix/issue-87-referrer-validation
• Update the betting module.

Implementation changes

• Modify bets.rs (around line 20) to validate the referrer address against a registry.

Test and commit

• Verify that bet attempts with invalid referrers are rejected or the referral is ignored.

Example commit message
fix: implement formal validation for referrer addresses in betting

Guidelines

• Security against referral gaming.
• Timeframe: 24 hours.

[chidinma000]

@chidinma000 has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

i will like to work on this

ℹ️ Repo Maintainers: To accept this application, review their application or assign @chidinma000 to this issue.

[drips-wave]

Congratulations, @chidinma000! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on March 30, 2026.

🧑‍💻 @chidinma000: 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.

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