fix(landing): return 404 for unknown library, blog, integration, model, and author slugs - #8587

Summary

• Unknown slugs under /library, /blog, /integrations, /models (provider and model), and the library/blog author pages returned 200 with a contradictory index, follow + noindex pair instead of a 404 (soft 404). These segments have a loading.tsx, so rendering an unknown slug streamed the loading shell with a 200 before the page called notFound()
• Set dynamicParams = false on those routes (every valid slug is known at build time via generateStaticParams), so unknown params 404 before rendering with the section's not-found.tsx. Author pages get generateStaticParams from the authors of published posts. This matches /customers/[slug], which already did this
• Docs sitemap no longer lists the docs root, which redirects to /introduction (already listed)

Type of Change

• Bug fix

Testing

• Ran the app locally: unknown library/blog/integration/model/author slugs now return 404 with the section not-found page; known pages return 200
• Revert check on the same server: dynamicParams = true → unknown slug 200, false → 404
• Crawled every library, blog, author, integration, and model URL in the local sitemap: all 531 return 200
• Model routes generate params from every provider with models (resellers included, matching what the pages render); all 20 provider and 289 model pages return 200 locally, unknown ones 404
• bun run lint, bun run type-check, bun run check:audits, block-registry check, docs-manifest:check, root bun run test (all passing); /cleanup passes found nothing beyond a comment tightening

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing (new tests pass the test-audit authoring gate)
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)