Make `--client` to be `true` by default

[brillout]

How about --no-client instead of --client? I.e. making it opt-out instead of opt-in.

That would make HatTip slightly more zero config.

[cyco130]

I agree with this.

Why would you use a Vite-based tool (instead of node, tsx, deno, wrangler dev etc.) if you're not interested in building client code. It's a frontend tool in the end.