[Feature request]: --changeDefaultThinking= should exist to allow effort/thinking to be set once for all

### What do you need?

API and model are already defined during the setup; why not the effort?

Since we have a difference between medium and high (or xhigh and max) effort for each model, and the baseline operations for a model are based on intelligence x effort x cost, we should be able to set the effort/thinking/reasoning level once (`--changeDefaultThinking=high`) to set it for all.

It can possibly be configured MANUALLY in `config.yaml` and/or be used with an alias/function like:

```sh
fabric() {
for arg in "$@"; do
case "$arg" in
--thinking|--thinking=*)
command fabric "$@"
return
;;
esac
done

command fabric --thinking=high "$@"
}
```

**But it should be trivial**, since Fabric is meant to ease this kind of friction.

Start by locating the CLI handling for --thinking and the loading of config.yaml, then trace how model effort or reasoning is selected during setup. Done should mean a --changeDefaultThinking=high setting applies to all models or operations unless an explicit per-command thinking value overrides it; the issue does not name a test or implementation file.

Written by the indexing model from the issue text.