[Bug] Scoped css not work in webpack examples

[Timeless0911]

Describe the bug

In a webpack example with scoped css in sfc, the css does not have scopeId binded.

<script setup lang="ts">
import { ref } from 'vue'
const msg = ref('')
</script>

<template>
  <div>
    <h1 class="text-red">Hello world</h1>
    <h2>{{ msg }}</h2>
    <input v-model="msg" type="text" />
  </div>
</template>

<style scoped>
.text-red {
  color: red;
}
</style>

Actual

.text-red {
  color: red;
}

Expected

.text-red[data-v-abcdefgh] {
  color: red;
}

Reproduction

https://github.com/unplugin/unplugin-vue/tree/main/examples/webpack

System Info

System:
    OS: macOS 14.6.1
    CPU: (10) arm64 Apple M1 Max
    Memory: 160.47 MB / 64.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 22.10.0 - ~/Library/Caches/fnm_multishells/1084_1747037734148/bin/node
    Yarn: 1.22.22 - ~/Library/Caches/fnm_multishells/1084_1747037734148/bin/yarn
    npm: 10.9.0 - ~/Library/Caches/fnm_multishells/1084_1747037734148/bin/npm
    pnpm: 10.12.4 - ~/Library/Caches/fnm_multishells/1084_1747037734148/bin/pnpm
    bun: 1.1.30 - ~/.bun/bin/bun
  Browsers:
    Chrome: 137.0.7151.120
    Safari: 17.6

Used Package Manager

pnpm

Validations

• Follow our Code of Conduct
• Read the Contributing Guide.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A, please open a GitHub Discussion instead.
• The provided reproduction is a minimal reproducible of the bug.

[sxzz]

🤡 I don't know how it works on Webpack, but PR welcome if anyone wants to work on that!