Allow customizing the thinking/status spinner messages

Feature request

Right now the status spinner shows random words while Claude is working (e.g. "Pondering", "Marinating"...), and there's no way to configure this list.

It would be nice to let users set their own text for these messages, either a single fixed string or a custom list to pick from randomly, via a setting in settings.json.

Motivation

Purely a fun/personalization request — no functional impact, just would be a nice touch to make the CLI feel more personal.