mig-af/GoCDN-Scanner ? reverse-engineered prompt

Build me a small Go command line tool that can scan a domain and find subdomains using passive public sources, then tell me which CDN each one is behind, like Cloudflare, Akamai, AWS CloudFront, Google, Fastly, Sucuri, and BunnyCDN.

I want it to be fully passive, so no active probing of the target itself. It should also have a mode where I can give it an IP address and check which CDN it belongs to. Make it feel like a simple one file style utility I can run from the terminal, with clear help text and a clean output table. If possible, include an option to save the results to a text file for later.

Please keep it lightweight, easy to build into a single binary, and make the interface straightforward for someone who just wants to run a quick recon check. Look up current docs online if you need to.