Add blockchain RPC health check indicator

[MissBlue00]

Task

Implement the blockchain RPC health indicator with Stellar Horizon check.

Details

• In apps/api/src/health/indicators/blockchain-rpc.health.ts
• Use @stellar/stellar-sdk to call server.getRoot()
• Verify Horizon responds with valid root object
• Log response time for monitoring

Path

• apps/api/src/health/indicators/blockchain-rpc.health.ts

Test

Run pnpm --filter api build to verify.

[jadonamite]

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

Hi maintainer can i work on this

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

[Agencybuilds]

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

i would love the opportunity to work on this issue, i'm motivated . detail oriented , and ready to contribute a solid solution while helping the community grow.

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