ocaml-claude: enable MDX on lib/control.mli
Run mdx on lib/control.mli so the two {[ ... ]} odoc blocks now
type-check. Used `open Claude` per the in-package convention,
qualified the error_detail call to its real path
(`Control.Response.error_detail`), and wrapped the
server_info-printing snippet in `let report client = ...` so the
example takes the client as input rather than referencing a free
binding. Switched Printf to Fmt.pr "%s@." for consistency.