The atr client returns json response by default rather than human readable messages

The ATR client returns json responses by default but I think CLI is moslty for people by default, so I think human output (coloured?) should be the default and some global parameter (--json) should turn it into json output.

Also there is no indictaion in --help currently how to change the output

Start by locating the ATR CLI entry point and the response-formatting code, then inspect the current --help output. The change is done when human-readable output is the default, a global --json option selects JSON output, and --help documents the choice; the desired coloring still needs clarification.

Written by the indexing model from the issue text.