Resolve generated API links to public pages and check built documentation #394

Part of #382 — v1.0.0 alpha readiness.

Problem

A read-only link audit of all 305 generated HTML pages at ebe9cca601fb85e6064c786367e546ded9b07d05 found 45 missing local target routes: 44 API routes and /examples/06-testing.

docs/components/signatureItem.astro:10-L13 links every WebAPI.X.y path as if X has a generated page. Internal modules such as FetchTypes and FileTypes are excluded from the public-page manifest, so those links point to nonexistent routes. Examples include /apidocs/fetch-types#headers and /apidocs/file-types#readableStream.

docs/pages/examples.astro:20 also uses a relative testing-guide link that resolves beneath /examples/ rather than to the actual /06-testing/ route.

Acceptance criteria

• Resolve internal type references to real public owner pages/anchors using the public API manifest, or render unlinked text where no valid public target exists.
• Fix the examples testing-guide link while respecting the deployed site base path.
• Add a post-build check for local page/asset links and fragment targets, with focused fixtures for internal types and base-path handling.
• The generated site has no unexplained missing local targets; document intentional exceptions explicitly.
• Retain filtering of implementation-only modules rather than publishing internal modules merely to satisfy broken links.
• npm run build:docs and the new link check run in CI/release validation.

Related: #23. A successful Astro build alone does not establish link correctness.