#631 Add Health Check Endpoint to Backend Express Server

[Olamidepy]

Closes #631

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This PR addresses #631 by implementing active backend dependency status monitoring on the /health endpoint. The endpoint now checks the health of the PostgreSQL database and the Redis cache before returning a status.

Key Changes

• Active Checks: Updated /health GET handler in src/index.ts to actively query the database (prisma.$queryRaw) and ping Redis (redis.ping()).
• Response Codes: Returns 200 OK if both services are online, or 503 Service Unavailable if any connection checks fail.
• Swagger Documentation: Documented the new response structure and HTTP status codes in Swagger OpenAPI specs.
• Mock & Unit Testing: Added a mock ping command in src/lib/redis.ts and introduced test cases in src/index.test.ts to cover healthy and failure states.
• Build Fixes: Resolved pre-existing duplicate type and type casting issues in sep12.controller.ts and queue-dashboard.route.ts to ensure clean compilation.

[Olamidepy]

@Ceejaytech25 Kindly merge

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