Encode `question_id` health: idempotent updates, deprecation, version

[mercy60]

Internal ID: #34

Imported from ISSUES.md via scripts/import-issues.mjs.

Problem Statement. There is no version field on Question. A future data model migration will be unsafe.

Expected Outcome. Add version: u32 to Question and a DataKey::SchemaVersion for migration support.

Acceptance Criteria.

• New tests assert bumping the schema version is a no-op for already-deployed contracts.

Implementation Notes.

• Migration story: read schema_version; on mismatch, error or migrate.

Files / modules affected.

• onchain/contracts/stellar_hunts/src/lib.rs
• onchain/contracts/stellar_hunts/src/test.rs

Dependencies. #27 (companion: tombstone / retirement lifecycle alongside versioning).

Difficulty / Effort. Medium / S (≈ 3 hours).

Labels. area:contracts, tech-debt

[Gogo-Eng]

@Gogo-Eng has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

i will love to work on this issue

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

[ybmaorg]

@ybmaorg has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi, I'd like to take this on.

I've worked on blockchain and Web3 projects, including Stellar and Soroban smart contracts, alongside traditional full-stack web development. I'm comfortable moving between frontend, backend, and on-chain work.

I've reviewed the issue and I'm confident I can implement a solid solution while following the project's conventions.

Happy to get started right away if assigned — looking forward to contributing.

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

[drips-wave]

Congratulations, @ybmaorg! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

🧑‍💻 @ybmaorg: 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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