feat: add backend REST endpoint POST /invoices/:id/release-escrow

[misrasamuelisiguzor-oss]

Description

Implement the POST /invoices/:id/release-escrow endpoint that enables an admin to trigger release_escrow on a paid invoice, transitioning it to the Released state. The endpoint enforces admin-only access and returns the updated status on success.

Requirements and context

• Enforce admin-only authorization before submitting the transaction
• Call release_escrow on the invoice contract via Soroban RPC
• Handle Unauthorized(1) from the contract with a 403 response
• Return updated invoice status (Released) and transaction hash on success
• Follow existing project conventions

Suggested execution

1. Fork the repo and create a branch

   git checkout -b feat/backend-post-invoice-release-escrow
   

2. Implement changes
3. Test and commit

Example commit message

feat: add backend REST endpoint POST /invoices/:id/release-escrow

Guidelines

• Assignment required before starting
• PR description must include: Closes #[issue_id]
• Keep PR description professional and detailed

[Emoji-dot]

@Emoji-dot 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

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[MK0042]

@MK0042 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I work actively in Node.js/Express and blockchain development. I've built and deployed production REST APIs across two platforms, with hands-on experience in payment state machines, role-based auth, and transactional edge cases.

Please I wish to work on this issue.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @MK0042 to this issue.

[Good-Coded]

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

Hi, I’d like to take on this issue.
I have experience working with smart contracts, backend systems, and frontend integrations, and I’m comfortable implementing solutions that are deterministic, secure, and aligned with existing architecture. I focus on writing clean, maintainable code with proper validation, error handling, and test coverage to ensure stability and reliability.
For this task, I will follow the existing code patterns in the repository, avoid breaking changes, and ensure the implementation passes all integrity checks. I will include comprehensive tests covering edge cases and expected behavior, and make sure everything integrates smoothly without introducing regressions or performance issues.
I’ll also provide clear documentation where needed so the changes are easy to understand and maintain going forward.
Let me know if you’d like me to proceed or if there are any specific considerations I should be aware of.

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

[drips-wave]

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

🧑‍💻 @Good-Coded: 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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