idea: Font weight should default to `400 700` instead of a single `400`

[qwerzl]

In order to reach a near zero-config behavior and to avoid confusion, the default font weight can be set to 400 700 instead of a single 400 in the upcoming v1.12.0 release after unjs/unifont#193 is merged.

@danielroe What do you think?

[danielroe]

I think that is reasonable (though I'd love to see about autodetecting weights in future).