TopGreener-Web/Rebate ? reverse-engineered prompt

Build me a simple online rebate app for internal use. I want a small web tool where someone can upload spreadsheet files for purchase orders, credit usage, and rebate data, then run the rebate calculation and see the results in a clean dashboard. It should support the existing sample Excel files in the repo, let me try a simulation mode, and show useful totals and breakdowns instead of just raw rows.

Please make it easy to export the results back out as Excel and JSON, since there are already export files in this project and I want that flow to keep working. If there is already Python logic for the rebate math, reuse that rather than rewriting it, and connect it to a basic web interface so a non technical person can use it in the browser. Include sensible validation, clear error messages, and a straightforward way to run it locally. If you need to, look up current docs online and wire everything together in the simplest reliable way.