[BUG] Installer reports `Windows is not supported` when trying to install on non-Windows OS

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Running bash install.sh reports Windows is not supported.

$ uname -s
FreeBSD

What Should Happen?

Installer should either work, or correctly report that the user's OS is not supported.

Error Messages/Logs

Steps to Reproduce

1. Install FreeBSD
2. Fetch https://claude.ai/install.sh
3. Run bash install.sh

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Not yet installed

Platform

Anthropic API

Operating System

Other

Terminal/Shell

Xterm

Additional Information

_No response_