moatasem-alhilali/my-whatsapp-bot-backend-js — reverse-engineered prompt

Build me a WhatsApp messaging backend API that can handle multiple WhatsApp accounts at the same time. I want to be able to create a session, get a QR code to log in, see whether each session is connected, log a session out or delete it, and send either plain text messages or media with an optional caption from a chosen session. Please make it feel solid and organized, with request validation, upload validation and size limits, safe error handling, a simple health check route, and configuration through environment variables for things like port, CORS origin, session storage, upload folder, max sessions, and file size. I also want browser friendly API docs I can open easily, plus support for both development and production runs. Using TypeScript is fine. If anything is unclear, look up the current docs online and wire the whole thing up end to end.