Add shareable topic paths to the research atlas

[aruintelligence]

What changed

• Give each atlas topic a stable, safe fragment link that reopens the matching filter on a fresh visit.
• Add a copy control that shares the topic only, leaving free-text search words out of the URL.
• Keep the root and Pages homepages mirrored.

Verification

• Inline scripts parse and HTML IDs are unique.
• node --test test/*.test.js (9/9 test files passed).
• Fresh deep-link and copy-control inspection after Pages deploy.