Add FeeManager fee-config commit-reveal scheme to prevent front-run fee changes

[greatest0fallt1me]

Description

Admin fee changes in fees.rs apply immediately on the next block, letting an admin front-run their own change against pending bets. Add a two-step commit-reveal: admin commits a hash of the new fee config first, then after a minimum delay reveals it. Bets in the delay window are settled under the old config.

Requirements and Context

• Commit stores BytesN<32> hash and the committed_at ledger
• Reveal verifies preimage and applies after min_delay_ledgers
• Re-commit overwrites pending commit
• 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/fee-config-commit-reveal

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

Example commit message

feat: add commit-reveal scheme for FeeConfigManager updates

Acceptance Criteria

• Reveal without commit fails
• Reveal before delay fails
• Mismatched preimage fails with specific error

Guidelines

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

[GBOYEE]

Hey! I can work on this. I will add a commit-reveal scheme to FeeManager so fee-config changes cannot be front-run. PR incoming shortly.

[samuelfrancis163-eng]

@samuelfrancis163-eng has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

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Congratulations, @samuelfrancis163-eng! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

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