Add admin migrate_developer_balance escape hatch with timelock

[greatest0fallt1me]

Description

This is a smart-contract issue for the GrantFox campaign. Admin-only entrypoint to move a developer's balance to a new address through a timelock for compliance recoveries.

Requirements and Context

• Propose + execute pair
• Subject to timelock
• Emits AdminMigration event
• Multisig auth
• 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/migrate-developer-balance

2. Implement changes
   • contracts/settlement/src/admin.rs
   • contracts/settlement/src/timelock.rs
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: admin migrate_developer_balance with timelock

Acceptance Criteria

• Propose stores
• Execute past window
• Event emitted
• Multisig honored

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

[emynogithub]

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

I have the skill it takes to work on this issue , please give me the opportunity to show my competence in problems solving

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

[Songu3020]

@Songu3020 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi, I'm Peter — a Full-Stack & Blockchain Developer with 3+ years of experience. I've reviewed this issue and I'm confident I can handle it. I'll submit a clean PR within 1-2 days max. Please assign it to me!

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Songu3020 to this issue.

[grantfox-oss]

🦊 GrantFox — @Songu3020 has been assigned to this issue as part of the Official Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #494)
2. Your PR will be reviewed by the CalloraOrg maintainers

Good luck! Track your progress on GrantFox.

[drips-wave]

Congratulations, @Songu3020! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @Songu3020: 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 as part of the Official Campaign campaign!

@Songu3020's PR #546 was approved and merged by @greatest0fallt1me.

🏆 @Songu3020: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (156 total points). Track your full progress on GrantFox.

👏 Great work, @Songu3020! Keep contributing to CalloraOrg.

[drips-wave]

This issue has been completed by @Songu3020 as part of the Stellar Wave Program's 6th Wave 🥳

😎 @Songu3020: 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. You can also Leave a review to share your experience working on this issue.

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