feat(docs): add consent-aware Google Analytics

[nick-csu]

Summary

• add consent-aware GA4 support to Cortex configuration
• configure docs.cortexdocs.dev and demo.cortexdocs.dev with G-KQW4ERPLHB
• restrict tracking to exact production hosts and preserve opt-out controls
• document and test the analytics configuration

Validation

• npm run test
• npm run build
• npm run lint
• npm run format:check
• npm audit --audit-level=high
• docs and demo production builds
• local static preview browser check