Add a health check endpoint returning database, Redis, and Stellar Horizon connectivity status

[Chucks1093]

Summary

There is no health check endpoint for the server, making it impossible for load balancers or uptime monitors to verify that all dependencies are reachable. A GET /health endpoint that probes the database, Redis, and Horizon and returns their status should be added.

Scope

• Add GET /health endpoint that does not require authentication
• Probe the database with a lightweight SELECT 1 query
• Probe Redis with a PING command
• Probe Stellar Horizon by fetching the root endpoint and checking for a 200 response
• Return 200 with a JSON body listing each dependency and its status (ok or degraded)
• Return 503 if any dependency is degraded, with the degraded dependencies listed

Acceptance Criteria

• 200 returned when all dependencies are healthy
• 503 returned when any dependency is degraded
• Response body lists database, redis, and horizon with individual statuses
• Endpoint responds within 2 seconds under normal conditions
• Endpoint accessible without a JWT

ETA: 12 hours

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Coordinate on Telegram

[Meet-hybrid]

I would like to contribute to this issue. I have experience with JavaScript/TypeScript, React, backend APIs, testing, Git, and software architecture. I will follow the acceptance criteria, add tests, and provide a focused pull request.

[Meet-hybrid]

I would like to contribute to this issue. I have experience with JavaScript/TypeScript, React, backend APIs, testing, Git, and software architecture. I will follow the acceptance criteria, add tests, and provide a focused pull request.