`chat read` hard-wraps output even if stdout !isatty

The culprit appears to be here in chat_cli_rendering; it doesn't bother checking if the output is a tty and instead blindly assumes that the width of the controlling terminal is the correct width to wrap at. This doesn't match common conventions for command line programs (which should not wrap at all if stdout is not a tty) and makes it harder to automatically process the output besides (I know the JSON API exists, but for some things having the message already rendered, reactji summed up, etc is very convenient).

Start in go/client/chat_cli_rendering.go at the referenced rendering logic and inspect how output width is selected. Reproduce chat read with stdout redirected rather than attached to a TTY, then verify that non-TTY output is not hard-wrapped while terminal output retains its existing behavior.