- Add health.rs module with start_health_check_listener() that binds to
127.0.0.1:{health_check_port} and serves GET /health returning 200 OK
with empty body
- Add health_route() in proxy/handler.rs for HTTPS listener fallback
- Add port conflict detection in config validation: health_check_port
must not conflict with listener ports on 127.0.0.1/localhost/0.0.0.0
- health_check_port = 0 disables the separate listener (handled at call
site)
- Add unit and integration tests for health check functionality
- Add [lib] target to enable integration test imports
- Add rcgen and reqwest dev-dependencies for TLS and HTTP test helpers
- Create src/config/test_fixtures.rs with test_static_config() and test_dynamic_config()
- Create tests/ with integration tests, HTTP test helper (TestUpstream), and TLS test helper (SelfSignedCert)
- Add Clone derives to StaticConfig and related structs for test fixture construction
- All existing tests continue to pass
