Pagefind fails when site is deployed with a non-empty baseUrl #2922

Environment

• MarkBind v7.2.1
• GitHub Pages project site
• Non-empty baseUrl (for example, /IT2900)

Description

Pagefind search fails on sites deployed under a subpath. The generated page defines the base URL as a top-level lexical binding:

<script>
  const baseUrl = '/IT2900'
</script>

However, packages/core-web/asset/js/pagefind-lazyloader.js reads it as a property of window:

const baseUrl = window.baseUrl || '';
const module = await import(`${baseUrl}/markbind/pagefind/pagefind.js`);

A top-level const does not create a window property. As a result, window.baseUrl is undefined, the fallback empty string is used, and Pagefind attempts to import from the domain root when the Pagefind <search /> UI is opened.

For a site with baseUrl: "/IT2900":

• Actual request: /markbind/pagefind/pagefind.js (404)
• Expected request: /IT2900/markbind/pagefind/pagefind.js (200)

The Pagefind assets are generated correctly at the expected subpath; only the lazy-loader import URL is incorrect.

Steps to reproduce

1. Configure a MarkBind site with a non-empty base URL and Pagefind enabled:

{
  "baseUrl": "/example",
  "pagefind": {
    "enablePagefind": true
  }
}

2. Add the Pagefind component <search /> to a page or layout. Note that <searchbar> is the separate legacy heading-search component and does not exercise this code path.
3. Run markbind build.
4. Serve _site so that it is available under /example.
5. Open the Pagefind search UI.
6. Observe that the browser requests /markbind/pagefind/pagefind.js instead of /example/markbind/pagefind/pagefind.js.

Suggested fixes

Either expose the generated value explicitly:

<script>
  window.baseUrl = '{{ baseUrl }}'
</script>

or have the lazy loader consume a value that is passed without relying on a window property.

Additional evidence

The issue is present in both the v7.2.1 generated output and the current master versions of packages/core/src/Page/page.njk and packages/core-web/asset/js/pagefind-lazyloader.js.