superdoc/docx-editor ? reverse-engineered prompt

Build me a modern DOCX editor that works right in the browser.

I want users to be able to open a Word file from a URL or upload a .docx file, see it rendered properly with pages, headers, footers, sections, and tables, then edit it and save changes back to the DOCX format without converting it into HTML first. It should also support a blank document when none is loaded.

Please include a clean editor view with a toolbar, basic document actions, and a simple landing page or demo screen so I can try it quickly. If it makes sense, add commenting, suggestions, track changes, and collaborative editing for multiple people at once. I also want the same core document handling to work in the browser and from code, so it can be used for automation or agent style workflows later.

Make it feel polished and easy to use, with a clear setup and sensible defaults.