Claude Code proxy: use lowercase https_proxy (and include http://)

@hao CC BY 4.0

While setting up Claude Code behind a proxy, I found that the uppercase env var HTTPS_PROXY wasn’t picked up, but the lowercase https_proxy worked.

One more gotcha: the proxy value needs to include the scheme (e.g., http://). Example:

export https_proxy=http://127.0.0.1:7890