fix(build): respect preserveSymlinks

[brc-dd]

Note that this is only supported when added through .vitepress/config.

closes #2779
closes #2351
closes #1496
closes #2153
closes #2335

Using something like this seems to work with symlinks:

// .vitepress/config.ts

import { defineConfig } from 'vitepress'

export default defineConfig({
  vite: {
    resolve: {
      preserveSymlinks: true
    }
  }
})

But the symlink support should still be treated as experimental. optimizeDeps + pnpm doesn't appear to work properly with this option and any warning can probably be ignored.