Revamp the public site shell

[jacobsd32-cpu]

Summary

• add a shared public-page shell for the marketing and docs surfaces
• rebuild pricing, certify, directory, docs, methodology, and blog around one enterprise-grade visual and copy system
• refresh developer and layperson positioning so the site consistently explains DJD as trust infrastructure instead of a loose mix of score/reputation pages

Validation

• npm run lint
• npm run typecheck
• npm test
• local Chromium screenshots for /pricing, /certify, /directory, /docs, /blog, and /methodology

Notes

• desktop and mobile spot-checks looked clean for the refreshed trust pages
• explorer and reviewer still use more dashboard-like layouts by design, but the public-facing product shell is now unified