[Aboyeji-Isaac]

Summary

Documents the backend's health checks, observability features, and metrics to make deployment, monitoring, and troubleshooting easier.

Changes

• Document the available health-check endpoints and their purposes.
• Explain the metrics endpoint, its output, and the metrics it exposes.
• Describe relevant environment variables and configuration options.
• Include guidance for deployment and monitoring integrations.
• Explain how operators can use the available observability information to investigate service health and performance.
• Keep the documentation aligned with the actual implementation.

Testing

• Review the documentation against the implemented endpoints and configuration.
• Verify that referenced paths, environment variables, and commands are accurate.

Closes #281