I currently rely on a heavily-macroed Excel workbook that does everything for me: • generates offers and proforma invoices, • pulls customer-specific prices and discounts the moment I type a name, • emails the document straight from the file, • lets me search products from a single cell, and • archives every invoice to a separate sheet so I can browse past transactions with one click. The file runs acceptably on Windows and macOS, but Android is a dead end because VBA and macros are unsupported. I now want all of that logic—and any sensible improvements—wrapped into a proper application that runs smoothly on Windows, macOS, and Android. A web-based or other cross-platform approach sounds logical as long as performance feels native; I’m open to your recommended stack. What matters most is that every workflow already available in the spreadsheet still works (or works better) inside the new app. I’ll supply the current Excel file, sample data, and a short walk-through video so you can reverse-engineer the logic. Please outline: • the technology you propose to use, • how you’ll migrate or connect to my existing data, • any UI/UX enhancements you envisage, • a realistic timeline with milestones, and • the cost breakdown. I’m looking for a smooth, install-and-go experience on desktop and an equally intuitive companion on Android. Let me know how you would build it and what ongoing support you can offer once we go live.