feat(backend): Add admin endpoint for contract registry rollback verification

[Viky207]

Problem

No verification endpoint for rollback.

Task

Add GET /contracts/registry/verify.

Acceptance Criteria

• Returns { name, version, wasmHash, deployedAt, actor }
• Compares against expected target
• 409 if mismatch
• Requires admin scope
• Emits verification event

[Dickson2015]

@Dickson2015 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

The issue description is crystal clear, Maintainer I would love to be given the opportunity to work on this issue just give me few hours thank you.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Dickson2015 to this issue.

[kceeglo345-dev]

@kceeglo345-dev has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

I would love to work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @kceeglo345-dev to this issue.

[drips-wave]

Congratulations, @kceeglo345-dev! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

🧑‍💻 @kceeglo345-dev: 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.

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