Add health endpoint and backend smoke test CI workflow

[mohab-elshamy]

This PR introduces a simple backend smoke test to ensure the application starts correctly and responds to basic health checks.

Changes

• Added a new /api/health endpoint returning Healthy
• Added a GitHub Actions workflow that:
  • Builds the backend
  • Starts the application without a launch profile
  • Polls the /api/health endpoint until the backend is ready

This helps detect startup issues early and improves CI reliability.

CI Smoke Test Results

Successful run	Failing run