Follow-up tests for a11y render-source metadata (PR #36264): render IT, FileRefView record, PageResourceHelper test

Summary

Follow-up test/quality work deferred from PR #36264 ("Expose page render source metadata for a11y agent"). The substantive correctness items from review (cross-host theme template cache-key bug, source-map permission gating) were fixed in that PR; this issue tracks the remaining test coverage and a style improvement so #36264 can merge without ballooning.

Tasks

1. End-to-end render IT for the #parse → #dotParse theme-shell switch (highest value)

PR #36264 changed the theme-shell include from #parse (filesystem, always working binary) to #dotParse (version-aware) for every file-asset-theme page — a high-blast-radius change on the hottest render path, currently with no end-to-end test. Add an IT that renders a file-asset-theme page asserting:

• EDIT mode: no stray data-dot-object='vtl-file' control is emitted for the theme shell (the one-shot dontShowThemeTemplateIcon suppression), while nested #dotParse includes (html_head/header/footer) still emit theirs.
• LIVE vs WORKING: publish template.vtl, then edit the working copy; assert LIVE renders the published version while PREVIEW/EDIT renders the working one.
• Scaffolding to reuse: ThemeDataGen, PageRenderTestUtil, HTMLPageAssetRenderedTest.
• Bonus: a cross-host case exercising the host-qualified template path (a page on host B rendering a theme owned by host A).

2. Convert FileRefView to a Java 25 record

Per review ("prefer records now that we are in Java 25"). Must verify the @Schema / Jackson serialization and OpenAPI generation remain byte-identical after the conversion (regenerate openapi.yaml and confirm no diff).

3. PageResourceHelper file-ref test

Add a unit/integration test for the toFileRef / widget file-ref building path (PageResourceHelper:~1265), covering extension lowercasing and the non-VTL fallback now that the API returns all theme files.

Context

• Parent: #36265
• Source PR: #36264
• Reviewer: @fabrizzio-dotCMS

Start with the scaffolding named in the issue: ThemeDataGen, PageRenderTestUtil, and HTMLPageAssetRenderedTest, then inspect the render path changed by PR #36264. Cover the EDIT and LIVE versus PREVIEW behavior, convert FileRefView while checking regenerated openapi.yaml, and add the PageResourceHelper:~1265 file-ref test for lowercasing and non-VTL fallback.