Function chatRepl

Runs an interactive chat loop: read a line with the brick's own input(), send it through brick.ask(), print the reply. Errors from ask() are printed and the loop continues. Resolves when an exit command is entered, the user presses Ctrl+C at the prompt or stdin closes (InputClosedError), or opts.signal aborts. Ctrl+C while a reply is being generated cancels just that turn.

Uses the brick's terminal-kit input rather than node:readline, so two libraries never fight over stdin raw mode.