Add safe AEO discovery and validation layer

[murraylovecode]

What changed

• added clear public-reading, canonical-publication and source-verification guidance
• added Organization, WebSite and CollectionPage metadata that matches visible content
• added a machine-readable project directory, sitemap, robots file and favicon
• added a standard-library pre-publication validator and pull-request check

Safety

• preserves every existing project URL and repository path
• does not alter research data, claims, report content or canonical report locations
• keeps the Executive Intelligence Index identified as repository-only
• does not touch Agentic Fabriq

Validation

• python3 scripts/validate_site.py
• desktop and 390px mobile visual review
• verified all linked project roots and the canonical research site return HTTP 200
• git diff --check