Festuwu/robloxinjector — reverse-engineered prompt

I want a small C# Windows desktop demo that shows how a host app can work with a separate DLL in a safe way for learning. Keep the basic idea of an injector style project with two parts, one app and one DLL, but make it only work with a simple local test program we include in the repo, not Roblox or any third party game or process.

The app should have a clean interface with buttons to pick the test program, load the demo DLL, show whether it connected, and unload or close cleanly. The DLL can do something harmless like write to a log, change a label in the test app, or pop a message so it is obvious it worked. Please make it easy to build and run on Windows, add comments, and include a short README with setup steps and what each part does. If anything is unclear, check current C# desktop docs online and choose the simplest approach.