Add invoice dispute mechanism with arbitration window

[Kingsman-99]

Overview

Add a dispute function that allows a payer to flag an invoice as disputed within 48 hours of funding. Disputed invoices cannot release funds until the dispute is resolved by the admin or the window expires.

Acceptance Criteria

• raise_dispute(invoice_id: u64, reason_hash: BytesN<32>) callable by any payer within 48 ledgers of full funding
• Disputed invoices enter Disputed status; release_funds is blocked with InvoiceDisputed error
• resolve_dispute(invoice_id, outcome: DisputeOutcome) callable only by admin
• DisputeOutcome: Approved (release funds to recipients) or Refunded (return funds to payers)
• If dispute is not resolved within 72 ledgers, it auto-expires and funds are released to recipients
• Emits DisputeRaised, DisputeResolved, DisputeExpired events
• get_invoice adds dispute: Option<DisputeStatus> to the invoice struct
• Integration tests: dispute → resolve approve, dispute → resolve refund, dispute → auto-expire

[DevSolex]

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

Hi Maintainer,

I’m a smart contract and full-stack developer and would love to contribute to this issue. I’m an experienced contributor with hands-on expertise in Rust, Soroban, Cairo, and TypeScript.

I’m passionate about building secure, scalable blockchain solutions, with a strong emphasis on writing clean and maintainable code. Based on the scope of this issue, I’m confident I can deliver a complete solution within 24 hours of assignment.

I’d greatly appreciate the opportunity to contribute and help move this forward.

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

[emteebug12-jpg]

@emteebug12-jpg has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi maintainers! I’d love to help out with this issue. I’ve checked the current codebase/documentation and know exactly what needs to be updated to make this clearer. I will ensure everything aligns perfectly with your existing contribution guidelines.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @emteebug12-jpg to this issue.

[brite-side0]

@brite-side0 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

hello dear maintainer i would love to work along side you on this task sir.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @brite-side0 to this issue.

[devcarole]

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

Hello maintainer, I would like to work on this issue.

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

[fairbid01]

@fairbid01 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I would like to work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @fairbid01 to this issue.

[drips-wave]

Congratulations, @brite-side0! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @brite-side0: 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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