marcmyworld/sf-workers ? reverse-engineered prompt

Build me a Cloudflare Worker that acts as a fast proxy for SourceForge downloads, so people in slower regions like India can get files more quickly.

I want it to take a SourceForge download URL, fetch the file through the worker, and serve it back with the right download headers so it still feels like a normal download. If it helps, add sensible caching and make sure large files stream properly instead of loading everything into memory.

Please keep it simple and clean, with the main logic in the worker code and the deployment config ready to go. If you need to check the latest Cloudflare docs or worker patterns, go ahead and look them up. Also make sure it handles basic errors well, like bad URLs or failed upstream requests, and returns a useful message instead of breaking.