Fix nested breadcrumbs

[Dobrunia]

Summary

• Renders breadcrumbs for deeply nested pages as first ancestor → ellipsis → current page so the header stays readable.

Before

After

[Copilot]

Pull request overview

This PR improves breadcrumb rendering for deeply nested documentation pages by collapsing long trails into a compact form to keep the header readable.

Changes:

• Add backend breadcrumb generation (first ancestor → ellipsis → current) and pass it into the page template.
• Update the page header Twig template to render breadcrumbs from a provided breadcrumbItems list.
• Adjust page header CSS flex/overflow rules to prevent breadcrumb overflow and ensure truncation behaves well.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/frontend/styles/components/page.pcss	Adds flex/overflow/ellipsis styling to keep long breadcrumb text from breaking the header layout.
src/backend/views/pages/page.twig	Switches breadcrumb rendering to iterate over breadcrumbItems (supports ellipsis + current page styling).
src/backend/utils/breadcrumbs.ts	Introduces breadcrumb-building helper and collapsing logic.
src/backend/routes/pages.ts	Uses buildPageBreadcrumbs and passes breadcrumbItems to the page view.
src/backend/routes/aliases.ts	Uses buildPageBreadcrumbs for alias-served pages and passes breadcrumbItems to the page view.
src/backend/models/page.ts	Adds getAncestorChain() to retrieve ancestors for breadcrumb construction.
src/backend/build-static.ts	Passes breadcrumbItems during static page rendering.
package.json	Bumps package version to 2.3.1.

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