Expose SeekersAI site architecture

[moose-lab]

Summary

• Expand the QuickFork public landing navigation into Product, Use Cases, Resources, Examples, Pricing, and free-brief CTA surfaces.
• Group the footer by Product, Use Cases, Resources, Examples, Support, and Legal/AI discovery links.
• Add marketing-page breadcrumbs and curated related-route links so published growth pages have stronger internal discovery.
• Add the SeekersAI site architecture plan document for the implemented route structure.

Test Plan

• npm test
• npm run build
• git diff --check
• Local smoke: / and /product/github-repo-to-launch-package returned 200 on Vite dev server

Notes

• Supersedes PR Expose SeekersAI site architecture #34 so the branch name matches the implementation scope.
• Did not merge locally because the main checkout currently has unrelated uncommitted changes that overlap several touched files.