[fontless] support infering full range of variable weight

[hi-ogawa]

🆒 Your use case

Currently the default is hard-coded as 400, but this is not ideal for many google fonts since the same font file can support wider range of font-weight if we infer full range.

fontaine/packages/fontless/src/defaults.ts

Line 6 in bd022dd

weights: [400],

🆕 The solution you'd like

Add support for this on unifont and enable it by default on fontaine for google font.
It appears unifont already has variable font detection https://github.com/unjs/unifont/blob/551259f1538c72184017cdd7d6dbc52958fef8ec/src/providers/google.ts#L83

Perhaps as experimental provider option such as:

google: {
  experimental: {
    inferVariableWeights: true,
  }
}

🔍 Alternatives you've considered

No response

ℹ️ Additional info

No response