sanny32/OpenModScan — reverse-engineered prompt

Build me a desktop app called OpenModScan, a free Modbus master client for Windows and Linux. I want a clean GUI where I can connect to devices over Modbus TCP and Modbus RTU, and also use RTU over TCP in the scanner if that makes sense. The app should let me read and write coils, discrete inputs, holding registers, and input registers, including single and multiple writes, plus mask write register. Please include a live Modbus log, a device address scan tool, a scanner view, a message parser, and a way to send custom user messages. It should feel like a practical utility for testing and troubleshooting industrial devices, not just a developer demo. Make sure it can be built from source with simple scripts for Windows PowerShell and Linux shell, and keep the app usable on both platforms. If anything is unclear, look up current docs online and make sensible choices.