Add per-block bet-rate limiter to RateLimiter to dampen flash-trading bursts

[greatest0fallt1me]

Description

rate_limiter.rs enforces a per-user token bucket but does not bound aggregate per-ledger bet volume, leaving the market open to micro-burst manipulation right before resolution. Add a per_ledger_bet_cap enforced inside place_bet/place_bets so the global bet rate per ledger cannot exceed an admin-set ceiling.

Requirements and Context

• New ledger-keyed counter under DataKey::PerLedgerBetCounter
• Resets implicitly when ledger sequence advances
• Configurable cap with sane default; admin-gated
• Must be secure, tested, and documented
• Should be efficient and easy to review

Suggested Execution

1. Fork the repo and create a branch

   git checkout -b feature/per-ledger-bet-cap

2. Implement changes
   • contracts/predictify-hybrid/src/rate_limiter.rs
   • contracts/predictify-hybrid/src/bets.rs
3. Test and commit
   • cargo test -p predictify-hybrid per_ledger_bet_cap
   • Cover edge cases
   • Include test output and notes in the PR

Example commit message

feat: enforce per-ledger bet cap in RateLimiter

Acceptance Criteria

• Cap is admin-set and read on every bet
• Counter rolls over with ledger advancement
• Bets above the cap fail with Error::PerLedgerBetCapExceeded

Guidelines

• Validate auth, overflow, and storage TTL/archival
• Clear documentation and inline comments
• Timeframe: 96 hours

[Ayomide-codex]

@Ayomide-codex has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Can I work on this. I am a good fit

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

[drips-wave]

Congratulations, @Ayomide-codex! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @Ayomide-codex: 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 🌊

[drips-wave]

This issue has been marked as completed by a Drips Wave moderator for @Ayomide-codex as part of the Stellar Wave Program's 6th Wave 🥳

Moderator's reason: [Auto-assessed] PR #797 correctly implements the per-ledger bet-rate limiter requested in issue #659, including storage keys, admin-gated configuration, and enforcement in the betting logic. Although the PR title is slightly mismatched, the code diff directly addresses the issue requirements and there are no maintainer objections.

😎 @Ayomide-codex: You earned 100 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.

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

ℹ️ Note: This issue was marked complete via moderation. Points were issued even though the GitHub issue remains open.