Add per-developer event archival pruning with FIFO cursor

[greatest0fallt1me]

Description

This is a smart-contract issue for the GrantFox campaign. Archive events older than N ledgers with a deterministic FIFO cursor to avoid storage TTL pressure.

Requirements and Context

• FIFO cursor key
• Archive batch size from env
• No event lost
• TTL on archive entries
• 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 task/event-archive

2. Implement changes
   • contracts/settlement/src/archive.rs (new)
3. Test and commit
   • Run the repo's standard test suite and lint
   • Cover edge cases; include output in the PR

Example commit message

feat: FIFO event archival pruning

Acceptance Criteria

• Cursor advances
• Batch size enforced
• No loss
• TTL on archive

Guidelines

• Minimum 95% test coverage with cargo test
• require_auth on every state-changing entrypoint
• Overflow-safe math; no unwrap() in production paths
• Clear NatSpec-style /// rustdoc
• Timeframe: 96 hours

[drips-wave]

@greatest0fallt1me Deyanju23 could not be assigned to this issue because they have reached the maximum of 4 accepted assignments per organization in the current wave of the Stellar Wave Program.

The assignee has been removed. Please choose a different contributor.

[Ajibose]

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

Kindly assign this to me

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

[uche102]

@uche102 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I would like to work on this

ℹ️ Repo Maintainers: To accept this application, review their application or assign @uche102 to this issue.

[Okorie2000-code]

@Okorie2000-code has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi Maintainer, I'd love to work on this issue. I understand the requirements and will submit a clean, well-tested PR.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Okorie2000-code to this issue.

[drips-wave]

Congratulations, @uche102! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @uche102: 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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