Add reject_issuer_transfer so the proposed new_issuer can explicitly decline a pending transfer

[thlpkee20-wq]

Description

The two-step issuer transfer flow lets the old issuer cancel_issuer_transfer, but the proposed new_issuer can only decline passively (by never accepting until expiry). Add reject_issuer_transfer(new_issuer, namespace, token) so the proposed party can immediately and verifiably decline, freeing the offering for a new proposal and emitting an auditable event.

Requirements and context

• Must be secure, tested, and documented
• Should be efficient and easy to review
• Relevant code: src/lib.rs (propose_issuer_transfer, accept_issuer_transfer, cancel_issuer_transfer, find_pending_transfer_for_new_issuer)
• Only the pending new_issuer may reject; emit a dedicated event

Suggested execution

• Fork the repo and create a branch
• git checkout -b feat/reject-issuer-transfer
• Implement changes
  • Reuse find_pending_transfer_for_new_issuer to locate the offering
  • Require new_issuer.require_auth() and remove PendingIssuerTransfer
  • Emit a new iss_rej event with (old_issuer, new_issuer)
• Validate security and correctness assumptions

Test and commit

• Run tests
  • cargo test
• Cover edge cases
  • Reject by wrong address, reject when no pending, re-propose after reject
• Include test output and security notes

Example commit message

feat: allow proposed issuer to reject pending transfer

Guidelines

• Minimum 95 percent test coverage
• Clear documentation
• Timeframe: 96 hours

[nnennaokoye]

@nnennaokoye has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

please assign this issue to me, i'll delver as soon as possible.

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[Topmatrixmor2014]

@Topmatrixmor2014 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

i am interested in working on this issue and i shall deliver promptly on this with qualitative feedback

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[Properprogress1]

@Properprogress1 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Having worked on this project in different waves, I'll love to work on this task

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Properprogress1 to this issue.

[drips-wave]

Congratulations, @Topmatrixmor2014! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

🧑‍💻 @Topmatrixmor2014: 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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