Replace default CORS middleware with explicit CORS configuration in test
server setup to align with production security settings. This ensures test
environment matches production behavior and prevents potential CORS-related
test failures.
Changes:
- Replace echomiddleware.CORS() with echomiddleware.CORSWithConfig()
- Configure allowed origins, methods, and headers explicitly
- Set AllowCredentials to false for test environment
- Add ExposeHeaders for Content-Length
This maintains consistency with the CORS configuration applied to the main
server in commit fb05c49.