docs: Add /api/health/health dependency probe

[Immaculate0606]

Summary

This PR adds a dependency health probe endpoint to /api/health/health, providing visibility into the status of the application's external dependencies. The endpoint performs health checks against configured services and returns a structured response indicating the availability and status of each dependency.

Closes #743

Changes

• Added /api/health/health dependency probe endpoint.
• Implemented health checks for external service dependencies.
• Returned standardized health status responses for all monitored dependencies.
• Added input validation and consistent error handling where applicable.
• Included structured logging with correlation IDs for improved observability.
• Added focused unit/integration tests covering the new functionality.
• Updated documentation to describe the new endpoint and its response format.

Testing

• Added tests for:

  • Successful dependency health checks.
  • Unavailable/failing dependencies.
  • Standardized error responses.

• Achieved the required coverage on changed lines.

• Verified linting and formatting compliance.

Security

• No sensitive dependency information or credentials are exposed in responses.
• Health checks are implemented with appropriate error handling and timeouts to prevent information leakage and unnecessary resource consumption.

API Changes

New Endpoint

GET /api/health/health

Returns the health status of the application's external dependencies, including their availability and overall health status.

Checklist

• Implements the requested feature.
• Added focused tests.
• Updated documentation.
• Follows project linting and code style.
• Includes input validation and standardized error handling.
• Uses structured logging with correlation IDs.
• Closes Add /api/health/health dependency probe #743

[greatest0fallt1me]

Solid PR — merging. Appreciate the effort!