fix: resolve @antfu/utils types in dts output

[daopk]

Description

Fix type resolution for the imports option — it was showing as any in TypeScript.

This PR updates the tsdown config to bundle @antfu/utils types in the generated .d.ts output:

dts: {
  resolve: ['@antfu/utils'],
},

This ensures proper type inference for the imports option and exposes supported presets correctly.

Linked Issues

Fixes #606

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