docusealco/docuseal ? reverse-engineered prompt

I want to build a self-hosted, open-source alternative to DocuSign. The main feature is allowing users to upload a PDF and then use a simple, visual drag-and-drop editor to add fields like signature boxes, date pickers, and text inputs directly onto the document.

Once a document is ready, I need to be able to send it to one or more people to fill out and sign electronically. The app should handle sending email invitations and securely store the final, signed documents. The signing experience has to be really smooth and mobile-friendly.

I'll also need basic user management so people on my team can have their own accounts. For the tech stack, let's go with Ruby on Rails for the backend and a modern frontend using Vue and Tailwind CSS. The whole thing should be containerized with Docker so it's easy for me to deploy on my own server.