rajsquare/billing-app ? reverse-engineered prompt

Build me a simple billing app for a small business.

I want something where I can add customers, create invoices, mark payments as paid or pending, and quickly see what is overdue. It should have a clean dashboard with totals for unpaid, paid, and overdue bills, plus a way to search or filter by customer and status. I’d also like basic pages for managing customers and invoices, and it should feel easy to use on desktop and mobile.

Keep the design straightforward and professional, with a modern look that would make sense for an accounting or invoicing tool. If anything is unclear, make sensible choices, and if you need to check current docs or best practices online, go ahead.