Fix & Extend Existing SaaS Backend API (Node.js) + Add One New Feature

We are looking for a Full Stack Engineer to help us with a small improvement task in our existing SaaS project. We already have a working application built with React and Node.js. We now need a developer to fix a few backend issues and implement a small new feature in our API layer. Tasks include: Debug and fix a few Node.js backend issues Improve or refactor existing REST API endpoints Add one small new feature to the backend (we will explain after hiring) Ensure smooth integration with the existing React frontend Clean, maintainable code changes only (no redesign required) This is a small, focused task for an experienced developer who is comfortable jumping into an existing codebase.