setup writes a .mcp.json in the checkout and only READS ~/.claude.json to copy
the server's settings. The old behaviour is setup --in-place.

Verified at the floor before tagging: a clean clone, system-resolved python3,
no dependencies installed, a fake HOME. Listed, wrapped, launched the proxy
(rc=0), read the receipt, uninstalled. Their config byte-identical throughout
and the literal token never printed.