[easy] Add data validation for imported contract verification records

[davedumto]

Summary

Contract verification records imported from external sources are not validated before being stored.

Requirements

• Add schema validation for imported record fields
• Reject and log records that fail validation with a clear reason
• Add tests covering valid and invalid import records
• Document the import validation rules in the service README

[jaymhorsh]

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

Kindly assign, having gone through the issues, I'm confident am best fit to resolve these issues.

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

[Nuelthewave]

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

Hi Maintainer! i can easily resolve this issue. i would appreciate if i'm appointed to work on it.

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

[drips-wave]

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

🧑‍💻 @Nuelthewave: 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 🌊

[drips-wave]

This issue has been completed by @Nuelthewave as part of the Stellar Wave Program's 8th Wave 🥳

😎 @Nuelthewave: You earned 200 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.

🧑‍💻 Repo maintainers: How'd the contributor do? Leave a review to share your experience working with them.