krystaldevrblx/rainstrap ? reverse-engineered prompt

Build me a lightweight Windows app that makes Roblox easier to install, launch, and manage. I want it to support both Roblox Player and Roblox Studio, handle updates, help repair common issues, and include a simple setup flow so someone can get started quickly without fuss.

It should also let me tweak a few performance and graphics settings, give me basic appearance customization, and manage only the fastflag options that Roblox currently allows. If a setting is not on the allowlist, just ignore it instead of trying to bypass anything.

Keep it clean and simple, focused on being fast and easy to use. Make it feel like a small launcher and settings tool for Roblox, not a big complicated app. If you need to check current docs or best practices online, go ahead and do that.