fix: align public navigation states

[Gnaroshi]

Summary

• enforce exactly one current item in Reading navigation across hash and nested routes
• make locale, footer, empty-state, About, and current-focus semantics truthful
• expose project/research evidence media and improve workflow/mobile navigation order
• add populated-feed, interaction, i18n, media, and visual regression coverage

Verification

• npm run check
• npm run check:i18n
• npm run check:public-tone
• npm run check:launch-content
• npm run check:links
• npm run test:e2e
• npm run test:a11y
• npm run test:smoke
• npm run test:feed-contract
• npm run test:visual
• npm run media:check
• npm run check:project-readiness