Oracle: add key provider health and rotation readiness

[Otaiki1]

Build location

Work primarily in oracle/src/keys. Keep related tests/docs beside that package unless this issue explicitly calls for a cross-package update.

Why this matters

The oracle supports local/HSM/KMS-like key management and should report health and rotation readiness without exposing secrets.

What to build

• Add health checks for configured key provider.
• Expose active key ID/fingerprint safely.
• Document rotation workflow and failure states.

Acceptance criteria

• Tests cover healthy provider, unavailable provider, and permission failure.
• Health output never includes private key material.

Suggested verification

cd oracle && npm run lint && npm run test && npm run build

[Michealshodipo56]

@Michealshodipo56 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

I would like to work on this issue kindly assign me

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Michealshodipo56 to this issue.

[wavyboy-build]

@wavyboy-build has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Dear maintainer, pls assign me this issue

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

[drips-wave]

Congratulations, @wavyboy-build! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

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