Create a secure ASP.NET Core API for a management system. The API will support user access, record management, filtering, and reporting. The implementation should follow clean coding practices, use clear validation, and be suitable for integration with an existing frontend application. The successful freelancer will be expected to work independently, share progress at agreed checkpoints, and raise questions early when a requirement needs clarification. All submitted work should be original, well organized, and ready for practical use after reasonable review.