vite config `root` is ignored on workspace

Describe the bug

Though we know maintaining cwd is tricky, can we respect explicit root config such as this?

// packages/client/vite.config.ts

import { defineConfig } from 'vitest/config';
import { join } from 'node:path';

export default defineConfig({
  // neither works
  root: './dir',
  // root: join(import.meta.dirname, './dir'),

  plugins: [
    {
      name: 'dump-root',
      configResolved(config) {
        // this is always "/abs-path-to/packages/client"
        // regardless of `root` config
        console.log('[dump-root]', config.root);
      },
    },
  ],
});

For example, this can affect Vite's project absolute path resolution as in the reproduction below.

Reproduction

https://stackblitz.com/edit/vitest-dev-vitest-rwukz2?file=packages%2Fclient%2Fvitest.config.ts

• npm run test fails
• npm run test-no-workspace succeeds

System Info

System:
    OS: Linux 5.0 undefined
    CPU: (8) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 18.20.3 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.2.3 - /usr/local/bin/npm
    pnpm: 8.15.6 - /usr/local/bin/pnpm
  npmPackages:
    @vitejs/plugin-react: ^4.2.1 => 4.3.3 
    @vitest/ui: latest => 2.1.4 
    vite: latest => 5.4.10 
    vitest: latest => 2.1.4

Used Package Manager

npm

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• 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 open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

Start with the workspace reproduction and packages/client/vite.config.ts. Run npm run test and npm run test-no-workspace, then trace how the workspace setup resolves the explicit root value reported by configResolved. Done means the configured root is respected and the reproduction passes with npm run test.